Post by Matt on Apr 26, 2007 17:43:56 GMT
gp3reps.wordpress.com/factory-problems/
When you first purchase your bike, there will be a few problems that need to be rectified before it is used to its full potential.
————————————————————————————————————-
Make sure you check that every nut and bolt on the bike are tight! Check the Lock Nut on the clutch! Someone nearly needed a new crank!
I suggest taking the lever off of your petrol tap when you run the bike, as it may end up on the track!
————————————————————————————————————-
Clutch
The first, and most important fault to fix is the clutch drum.
Basically, there is to much movement on the drum, which causes the clutch to burn out (which is likely to result in a new clutch and drum).
It is, however, an easy problem to fix.
Behind the water pump wheel, on the right hand side of the bike (take the pull start mechanism off) you will notice a washer. This washer belongs on the clutch side, so remove it.
Removing this washer will also prevent the water pump belt rubbing on the stator plate.
Take the clutch cover off and remove the lock nut on the clutch (It is a REVERSE thread, so make sure that you turn the nut CLOCKWISE to undo it). With a clutch pulling tool, remove the clutch, and then take the clutch drum off (be careful not to let the bearing/seel fall out of the middle). Place the washer (that you removed from the water wheel) onto the shaft and replace the clutch drum. This will take up the slack (you may need to put another small washer on to take up any slack-if there is still some left).
Next replace your clutch, and using a clutch holding tool, tighten the lock nut (to tighten the lock nut, turn it ANTI-CLOCKWISE). Check that there is no movement on the clutch drum, and replace the clutch cover.
If you find that there is still some wear on the clutch, change your springs to either blues or yellows (polini type springs because different makes use the colours, for different grades)-depending on your weight. Yellows normally work for most. You will find that the clutch bites at a better rev range, so you will no longer get the sluggish start!
It may also be worth while to purchase Genuine Polini Clutch Shoes, especially if you intend to race.
If you have already worn your clutch, you can buy GP3 copy clutches from here they cost £11.99, so are alot better value than the Genuine Polini shoes. However, you will not get the same performace. Email me with any clutch questions.
Don’t forget that you have to buy a REVERSE Clutch!-The standard ones will NOT fit!
Clutch Springs
Clutch springs provide resistance towards the clutch shoes. When this resistance is over powered by centerfrugal force, they allow the shoes to move outwards and ‘bite’ the clutch drum. Springs come in 3 different sizes, light, medium and heavy. Different sizes create different biting points.
Spring sizes for Polini are:
Blue = 2.1mm(light)
Yellow = 2.3mm(medium)
Red = 2.5mm(heavy)
Light springs are used when low (early) engagement of the clutch is needed, medium when medium engagement is needed, and heavy when later engagement of the clutch is needed.
Exhaust
I highly recommend having your exhaust repacked. The easiest way to do this is to take your end can off.
To do this, first remove your seat unit by removing the six bolts that hold it. Next undo the large nut underneath which holds the end can (it should have a rubber mount aswell) Undo the two bolts that hold the end can onto the exhaust pipe and remove the end can. With a little force you pull of the metal plate on the end of the can (the peice that was on the exhaust pipe end), and the simply push exhaust packing into the can. You may also want to drill a few extra holes into the baffle.
You can purchase this from most bike shops. It will make the bike run much quieter, and improve the performance.
Coil
If you find that the your bike is loosing revs, or begining to become unresponsive, it is likely that your coil has broken down. It may feel like your bike is being starved of fuel. This is a common fault, and should be replaced with a Genuine Polini Part. The part number is 143.600.003 and it costs £26.31
This will also allow the bike to rev up to 16,000 rpm. This is becase the Chinese coils begin to break down as the engine revs higher, so you loose 1000rpm.
Bearings
Alot of people also replace the small end with a Genuine Polini Part or BZM Part. This will help improve the bikes performace, and is a must if you plan to race.
The bearings in general are not great on these bikes either, so it is a good idea to change as many as you can, such as the transfer shaft bearing-as these wear very quickly. Don’t worry though, its not essential and they will not let you down straight away. Make sure when you do change them though, they are Genuine Polini Parts.
Seals
With both the Genuine engines and the rep engines, there tends to be leaks around the seals. Obviously, on the reps its a little more common, so replace them all as soon as you can. You may find that there is a slight oil leak, which you can identify, if not from anything else, if there is oil in the bottom of the clutch cover. If this is so, replace the oil seal as soon as you can. This is a very commom fault.
Sprockets
A good performance ungrade is to buy a rear sprocket adapter. The Genuine Polini Bikes have 4 bolts holding on the rear sprocket, but the reps only have 3. It is because of this that it is hard to get different sized sprockets. Paul Robinson can supply the sprocket adapters for £10 (this will mean that you can fit Genuine Polini Sprockets). You can get in touch with him on 07815525121 or email him at: paul@paulrobinson.wanadoo.co.uk
He can also suply chinese reverse clutches for about £25
If you don’t want to buy an adapter, you can ring ‘minimoto racing’ on 01666 838234
They stock light weight Talon sprockets to fit the GP3 reps, for only £15. It is very worthwhile to change the sprocket, no matter which of those two routes you take
Chain/Chain Roller
If you find that your chain keeps slipping off while you riding, it may be worth while to by a chain roller. This will keep the chain tense all of the time. However, there is normally no poblem if the chain is tight. It will, obviously, stretch in your first few rides, but after that it should settle.
You can purchase chain rollers for GP3’s from www.minimotosouth.co.uk, and they will bolt straight onto the swingarm.
The alternative is to make your own! The picture above should help
If you do find that your chain is continuously stretching, buy a new, after market part. Do not by a cheap chinese one!
Change your chain as soon as you can anyway to maximise your performace.
Carb
It is possible to squeeze an extra 2.3hp out of your bike, just by changing the brass inserts to Genuine Dellorto Parts. Scott Finlay can supply these kits, for about £40. They are definetly worth while, and a must if you plan to race. You can get in touch with him at www.minimoto.co.uk or ring him on 01666 838234
The standard main jet is an 89, but you can run up to a 120. Obviously, this is something that you should experiment with as different people have different preferences.
To sort out the over/under fueling of the bowl you need to set your floats up, for this you will need a vernier. Remove the carb from your bike (just unscrew the jubiliee clip), and unscrew the float bowl. Rest the carb on a level surface with the air filter side on the surface.
You now need to measure from left to right, from the carb base to the end of the float.
The distance should be 16mm, give or take 0.5mm.
Mark Blowers bike was flooding out petrol into the airfilter, and when he measured, it was 19mm. Since adjusting he has had no problem.
Note: you must check both sides of the float, as i have known one side to be 19mm and the other to be 16.5mm.
Check this diagram if you need help:
Air Filter
The air filter that these bikes come with are terrible. Eventually they break up, and begin to get sucked through the air filter (not a good thing!) I suggest replacing them with a Genuine Polini Part, because they are good, although this is not essential as there are many other good makes of air filter out there, such as Malossi. You should spend about £26, and purchase something like this:
Choke
On most of the replica bikes, the choke does not close properly, which causes the mixture to be incorrect. As a result, it is possible that your bike may eventually seize!
The problem is that the O-Ring doesnt seal. It is, however, an easy problem to fix.The picture shows the choke in its normal state, and as you can see, the O-Ring is still visible.
To make the choke work, you have to use a couple of fibre washers (which you place onto the bottom of the choke lever-you will need to take the plunger out of the carb)
This is how the choke should look when you have put the fibre washers on-as you can see, it now seals correctly (you will have to experiment with the washers, as the measurements are all different
The other option is to buy a Dellorto Choke.
Water Cap
Check that the water cap on your header tank (for the radiator-it is found underneath the petrol tank) is making a good seal, because if it leaks there is a chance of blowing your head gasket. Its a good idea to buy a new cap. Fiat Punto caps fit perfectly and only cost about £5. Don’t get caught out!
Seat Hight
The specs say that the seat hight is adjustable. The subframe (this is the part attched onto the actual frame at the back-where the seat sits) is held on by one bolt on each side. You will notice, however, that there are two extra holes that the bolt can be placed (see the picture). To change the seat position, just simply take out the bolts and put them into a different whole. Simple.
This changes the position more than the height, and gives more/less flex in the frame. The only way to find the best setting for you is to try them all.
Checks
Make sure that you use water in the radiator! Not anti-freeze. Tracks will only allow water, as anything else can cause hazards if there are leaks.
Because of this, it is essential that you keep the bike in an enclosed (warm) environment! You don’t want the water to freeze and bust your cylinder.Check the whole system for leaks, and make sure that all of the pipes are tight! Keep your header tank topped up to. The water level shouldn’t change much if you have checked for the leaks!
Check every single bolt on the bike, and remember to keep checking your lock nut on the clutch (its a revese thread).
Always start your bike before you take it anywhere and check it over for any rattles. Do not over stress the engine (by reving it highly) when the engine is cold!
Make sure that your breaks are tight and working effectivly.
Oil
I suggest using high performance pre-mix, synthetic 2 stoke oil, as it is a far better product performance wise, and is much better for the engine-it will make alot of difference. It’s more expensive, but for how much fuel these bikes use, its well worth the money. Mix it at 50/1.
Use high performance gearbox oil, not the rubbish the bikes come with. You can use the same grade though.
[glow=red,2,300]Now it’s time to ride![/glow]
Remember, these bikes are race machines, and as a result are very fast! Only ride them if you consider yourself qualified.
When you first purchase your bike, there will be a few problems that need to be rectified before it is used to its full potential.
————————————————————————————————————-
Make sure you check that every nut and bolt on the bike are tight! Check the Lock Nut on the clutch! Someone nearly needed a new crank!
I suggest taking the lever off of your petrol tap when you run the bike, as it may end up on the track!
————————————————————————————————————-
Clutch
The first, and most important fault to fix is the clutch drum.
Basically, there is to much movement on the drum, which causes the clutch to burn out (which is likely to result in a new clutch and drum).
It is, however, an easy problem to fix.
Behind the water pump wheel, on the right hand side of the bike (take the pull start mechanism off) you will notice a washer. This washer belongs on the clutch side, so remove it.
Removing this washer will also prevent the water pump belt rubbing on the stator plate.
Take the clutch cover off and remove the lock nut on the clutch (It is a REVERSE thread, so make sure that you turn the nut CLOCKWISE to undo it). With a clutch pulling tool, remove the clutch, and then take the clutch drum off (be careful not to let the bearing/seel fall out of the middle). Place the washer (that you removed from the water wheel) onto the shaft and replace the clutch drum. This will take up the slack (you may need to put another small washer on to take up any slack-if there is still some left).
Next replace your clutch, and using a clutch holding tool, tighten the lock nut (to tighten the lock nut, turn it ANTI-CLOCKWISE). Check that there is no movement on the clutch drum, and replace the clutch cover.
If you find that there is still some wear on the clutch, change your springs to either blues or yellows (polini type springs because different makes use the colours, for different grades)-depending on your weight. Yellows normally work for most. You will find that the clutch bites at a better rev range, so you will no longer get the sluggish start!
It may also be worth while to purchase Genuine Polini Clutch Shoes, especially if you intend to race.
If you have already worn your clutch, you can buy GP3 copy clutches from here they cost £11.99, so are alot better value than the Genuine Polini shoes. However, you will not get the same performace. Email me with any clutch questions.
Don’t forget that you have to buy a REVERSE Clutch!-The standard ones will NOT fit!
Clutch Springs
Clutch springs provide resistance towards the clutch shoes. When this resistance is over powered by centerfrugal force, they allow the shoes to move outwards and ‘bite’ the clutch drum. Springs come in 3 different sizes, light, medium and heavy. Different sizes create different biting points.
Spring sizes for Polini are:
Blue = 2.1mm(light)
Yellow = 2.3mm(medium)
Red = 2.5mm(heavy)
Light springs are used when low (early) engagement of the clutch is needed, medium when medium engagement is needed, and heavy when later engagement of the clutch is needed.
Exhaust
I highly recommend having your exhaust repacked. The easiest way to do this is to take your end can off.
To do this, first remove your seat unit by removing the six bolts that hold it. Next undo the large nut underneath which holds the end can (it should have a rubber mount aswell) Undo the two bolts that hold the end can onto the exhaust pipe and remove the end can. With a little force you pull of the metal plate on the end of the can (the peice that was on the exhaust pipe end), and the simply push exhaust packing into the can. You may also want to drill a few extra holes into the baffle.
You can purchase this from most bike shops. It will make the bike run much quieter, and improve the performance.
Coil
If you find that the your bike is loosing revs, or begining to become unresponsive, it is likely that your coil has broken down. It may feel like your bike is being starved of fuel. This is a common fault, and should be replaced with a Genuine Polini Part. The part number is 143.600.003 and it costs £26.31
This will also allow the bike to rev up to 16,000 rpm. This is becase the Chinese coils begin to break down as the engine revs higher, so you loose 1000rpm.
Bearings
Alot of people also replace the small end with a Genuine Polini Part or BZM Part. This will help improve the bikes performace, and is a must if you plan to race.
The bearings in general are not great on these bikes either, so it is a good idea to change as many as you can, such as the transfer shaft bearing-as these wear very quickly. Don’t worry though, its not essential and they will not let you down straight away. Make sure when you do change them though, they are Genuine Polini Parts.
Seals
With both the Genuine engines and the rep engines, there tends to be leaks around the seals. Obviously, on the reps its a little more common, so replace them all as soon as you can. You may find that there is a slight oil leak, which you can identify, if not from anything else, if there is oil in the bottom of the clutch cover. If this is so, replace the oil seal as soon as you can. This is a very commom fault.
Sprockets
A good performance ungrade is to buy a rear sprocket adapter. The Genuine Polini Bikes have 4 bolts holding on the rear sprocket, but the reps only have 3. It is because of this that it is hard to get different sized sprockets. Paul Robinson can supply the sprocket adapters for £10 (this will mean that you can fit Genuine Polini Sprockets). You can get in touch with him on 07815525121 or email him at: paul@paulrobinson.wanadoo.co.uk
He can also suply chinese reverse clutches for about £25
If you don’t want to buy an adapter, you can ring ‘minimoto racing’ on 01666 838234
They stock light weight Talon sprockets to fit the GP3 reps, for only £15. It is very worthwhile to change the sprocket, no matter which of those two routes you take
Chain/Chain Roller
If you find that your chain keeps slipping off while you riding, it may be worth while to by a chain roller. This will keep the chain tense all of the time. However, there is normally no poblem if the chain is tight. It will, obviously, stretch in your first few rides, but after that it should settle.
You can purchase chain rollers for GP3’s from www.minimotosouth.co.uk, and they will bolt straight onto the swingarm.
The alternative is to make your own! The picture above should help
If you do find that your chain is continuously stretching, buy a new, after market part. Do not by a cheap chinese one!
Change your chain as soon as you can anyway to maximise your performace.
Carb
It is possible to squeeze an extra 2.3hp out of your bike, just by changing the brass inserts to Genuine Dellorto Parts. Scott Finlay can supply these kits, for about £40. They are definetly worth while, and a must if you plan to race. You can get in touch with him at www.minimoto.co.uk or ring him on 01666 838234
The standard main jet is an 89, but you can run up to a 120. Obviously, this is something that you should experiment with as different people have different preferences.
To sort out the over/under fueling of the bowl you need to set your floats up, for this you will need a vernier. Remove the carb from your bike (just unscrew the jubiliee clip), and unscrew the float bowl. Rest the carb on a level surface with the air filter side on the surface.
You now need to measure from left to right, from the carb base to the end of the float.
The distance should be 16mm, give or take 0.5mm.
Mark Blowers bike was flooding out petrol into the airfilter, and when he measured, it was 19mm. Since adjusting he has had no problem.
Note: you must check both sides of the float, as i have known one side to be 19mm and the other to be 16.5mm.
Check this diagram if you need help:
Air Filter
The air filter that these bikes come with are terrible. Eventually they break up, and begin to get sucked through the air filter (not a good thing!) I suggest replacing them with a Genuine Polini Part, because they are good, although this is not essential as there are many other good makes of air filter out there, such as Malossi. You should spend about £26, and purchase something like this:
Choke
On most of the replica bikes, the choke does not close properly, which causes the mixture to be incorrect. As a result, it is possible that your bike may eventually seize!
The problem is that the O-Ring doesnt seal. It is, however, an easy problem to fix.The picture shows the choke in its normal state, and as you can see, the O-Ring is still visible.
To make the choke work, you have to use a couple of fibre washers (which you place onto the bottom of the choke lever-you will need to take the plunger out of the carb)
This is how the choke should look when you have put the fibre washers on-as you can see, it now seals correctly (you will have to experiment with the washers, as the measurements are all different
The other option is to buy a Dellorto Choke.
Water Cap
Check that the water cap on your header tank (for the radiator-it is found underneath the petrol tank) is making a good seal, because if it leaks there is a chance of blowing your head gasket. Its a good idea to buy a new cap. Fiat Punto caps fit perfectly and only cost about £5. Don’t get caught out!
Seat Hight
The specs say that the seat hight is adjustable. The subframe (this is the part attched onto the actual frame at the back-where the seat sits) is held on by one bolt on each side. You will notice, however, that there are two extra holes that the bolt can be placed (see the picture). To change the seat position, just simply take out the bolts and put them into a different whole. Simple.
This changes the position more than the height, and gives more/less flex in the frame. The only way to find the best setting for you is to try them all.
Checks
Make sure that you use water in the radiator! Not anti-freeze. Tracks will only allow water, as anything else can cause hazards if there are leaks.
Because of this, it is essential that you keep the bike in an enclosed (warm) environment! You don’t want the water to freeze and bust your cylinder.Check the whole system for leaks, and make sure that all of the pipes are tight! Keep your header tank topped up to. The water level shouldn’t change much if you have checked for the leaks!
Check every single bolt on the bike, and remember to keep checking your lock nut on the clutch (its a revese thread).
Always start your bike before you take it anywhere and check it over for any rattles. Do not over stress the engine (by reving it highly) when the engine is cold!
Make sure that your breaks are tight and working effectivly.
Oil
I suggest using high performance pre-mix, synthetic 2 stoke oil, as it is a far better product performance wise, and is much better for the engine-it will make alot of difference. It’s more expensive, but for how much fuel these bikes use, its well worth the money. Mix it at 50/1.
Use high performance gearbox oil, not the rubbish the bikes come with. You can use the same grade though.
[glow=red,2,300]Now it’s time to ride![/glow]
Remember, these bikes are race machines, and as a result are very fast! Only ride them if you consider yourself qualified.
