Hi All, this my 1st post and its a confusing one for me, i've recentlyy purchased a yb100 deluxe and have a slight problem, the top speed is just over 45mph, it pulls away well in 1st and 2nd but in third it seems to pull back at high revs like its choking up then in 4th it runs ok but only reaches approx 45mph, i've put a new plug in and had a mechanic friend check the head was ok but that was all he would do as he's a car mechanic and didn't want to get involved in the bike, another friend of mine said to put 2 head gaskets on it to lift the head and get more compression but i'm no mechanic and i've never heard of this, can anyone help please, cheers alec

Hi All, this my 1st post and its a confusing one for me, i've recentlyy purchased a yb100 deluxe and have a slight problem, the top speed is just over 45mph, it pulls away well in 1st and 2nd but in third it seems to pull back at high revs like its choking up then in 4th it runs ok but only reaches approx 45mph, i've put a new plug in and had a mechanic friend check the head was ok but that was all he would do as he's a car mechanic and didn't want to get involved in the bike, another friend of mine said to put 2 head gaskets on it to lift the head and get more compression but i'm no mechanic and i've never heard of this, can anyone help please, cheers alec

Not really sure of the problem you have could be carb related, or possibly ignition/plug issues.

Does it tick over ok, whats it like on fuel, any funny noises, choke on/off, when was it last serviced, these are just a few questions. The one thing i will say tho is sticking 2 head gaskets in is complete coblers and your mate wants a kick in the n4dds for even sugesting it.

Not really sure of the problem you have could be carb related, or possibly ignition/plug issues.

Does it tick over ok, whats it like on fuel, any funny noises, choke on/off, when was it last serviced, these are just a few questions. The one thing i will say tho is sticking 2 head gaskets in is complete coblers and your mate wants a kick in the n4dds for even sugesting it.

ticks over great good on fuel chokes off, just taken side casing off the engine to check carb and the paper gasket that goes around cover is nackered would this make a difference as i said i'm no mechanic, cheers for fast reply

First thing i would check is the baffle in the exhaust to make sure its not blocked with oil /carbon. Tony

Hi Alec, Might be a blocked exhaust or exhaust baffle, have a look at the baffle, if its the tube type clean it with a blowlamp and wire brush.

...Paul

ticks over great good on fuel chokes off, just taken side casing off the engine to check carb and the paper gasket that goes around cover is nackered would this make a difference as i said i'm no mechanic, cheers for fast reply

Doesn't make any difference.

You need to start from the beginning:

1. How long have you had the bike - or have you just got it?

2. Was it running up until you got it without problems, or has it been standing?

Assuming that you have just got it and it wasn't being used daily without problem it sounds like a carb problem - but could be other things as well/instead.

Before you start check compression - if you don't have a tester use your thumb over the plug hole - if it gets blown off when you kick the bike over compression should be ok.

Assuming compression is ok you need to:

1. Remove and clean the carb thoroughly - blow out all the airways and check there are no blockages in the jets - particularly the main jet as your problem doesn't appear to be slow running. Put the carb back see if it makes a difference.

2. Check the oil pump settings - I can mail you these if you need them.

3. Look at (through the generator) the condition of the points if they are pitting you can get arcing which affects spark particularly under load. If they are pitted or arcing you will need to replace (about £5 on ebay - but you need to get the generator flywheel off with a puller), and setting them up is fiddly, again I can send you details.

4. Check the connection at the plug cap - sometimes this suffers in the elements, if so cut a small section off and screw the cap back on assuming connection is not corroded.

5. If you replace the points and still get arcing you need to replace the condensor.

6. Make sure you have a new plug BH7S should be the NGK plug.

You should be able to get 60mph out of this bike top speed so 45 shows there is a problem somewhere - if the above don't rectify the problem it could be a crankcase sealing or clutch problem.

Let us know how you get on.

Good luck.

Doesn't make any difference.

You need to start from the beginning:

1. How long have you had the bike - or have you just got it?

2. Was it running up until you got it without problems, or has it been standing?

Assuming that you have just got it and it wasn't being used daily without problem it sounds like a carb problem - but could be other things as well/instead.

Before you start check compression - if you don't have a tester use your thumb over the plug hole - if it gets blown off when you kick the bike over compression should be ok.

Assuming compression is ok you need to:

1. Remove and clean the carb thoroughly - blow out all the airways and check there are no blockages in the jets - particularly the main jet as your problem doesn't appear to be slow running. Put the carb back see if it makes a difference.

2. Check the oil pump settings - I can mail you these if you need them.

3. Look at (through the generator) the condition of the points if they are pitting you can get arcing which affects spark particularly under load. If they are pitted or arcing you will need to replace (about £5 on ebay - but you need to get the generator flywheel off with a puller), and setting them up is fiddly, again I can send you details.

4. Check the connection at the plug cap - sometimes this suffers in the elements, if so cut a small section off and screw the cap back on assuming connection is not corroded.

5. If you replace the points and still get arcing you need to replace the condensor.

6. Make sure you have a new plug BH7S should be the NGK plug.

You should be able to get 60mph out of this bike top speed so 45 shows there is a problem somewhere - if the above don't rectify the problem it could be a crankcase sealing or clutch problem.

Let us know how you get on.

Good luck.

hi could you email the oil pump settins please the rest i'll have a go at tomorrow, many thanks alec,

[email protected]

hi could you email the oil pump settins please the rest i'll have a go at tomorrow, many thanks alec,

[email protected]

No probs will do so later today.

Ok an update, i removed baffles and cleaned them tried bike without and ran the same, stripped carb down cleaned jets with blow gun re-assembled with new gaskets and seals runs the same, advised by bike shop to turn the mixture screw in till it just pinches then wind out 1.5 turns still the same, had points checked and they look new no arcing and good spark, it still pulls back on high revs, need some advise or if local to maidstone help with carb adjustments, one change though the speedo is still reading approx 45-48 mph but my mate clocked me at 52mph so either my speedo or his is out, and he said there was white smoke untill i reached top speed. ANY IDEAS ANYONE, cheers alec

Ok an update, i removed baffles and cleaned them tried bike without and ran the same, stripped carb down cleaned jets with blow gun re-assembled with new gaskets and seals runs the same, advised by bike shop to turn the mixture screw in till it just pinches then wind out 1.5 turns still the same, had points checked and they look new no arcing and good spark, it still pulls back on high revs, need some advise or if local to maidstone help with carb adjustments, one change though the speedo is still reading approx 45-48 mph but my mate clocked me at 52mph so either my speedo or his is out, and he said there was white smoke untill i reached top speed. ANY IDEAS ANYONE, cheers alec

Hi - I am Ashford - could come and have a look if you are free sometime?

Let me know..

Hi - I am Ashford - could come and have a look if you are free sometime?

Let me know..

hi that would be great if you wouldn't mind, i'm in chart sutton between headcorn and maidstone t/c i'm unemployed at the moment so am free nearly every day whenever is good for you, kindest regards alec

Have you checked the air filter ? If i remember rightly this is a foam filter and can be washed out and lightly reoiled. Another thing i would check is to make sure the exhaust port isn't carboned up. You can check this by undoing the ring nut where the pipe goes onto the cylinder and shining a torch up there with the piston at bottom dead centre. You said your friend said there was a lot of white smoke. Check your gearbox oil level as it could be burning gearbox oil through the RH side crank seal. Tony.

hi that would be great if you wouldn't mind, i'm in chart sutton between headcorn and maidstone t/c i'm unemployed at the moment so am free nearly every day whenever is good for you, kindest regards alec

I'll PM you about arranging a time

A very big thanks to Fosdyke for coming round and sorting the problem out for me, he had it sorted in 5 mins,

thanks again Geoff

What was the problem ?

Sorry forgot to say the problem was the oil settings were well out, fosdyke did the business i took it down the road and it runs LOVELY, he even followed me and clocked me at 55mph and still creeping up, so i definately need new speedo or cable not sure which .

How did he solve it ? I'm having the exact same problem being stuck at 40mph 

 

Hi Ginger, this thread is 8 years old mate, unlikely that anyone from then will answer your query. Best to say Hi in the New members section then ask your question in the "general" area on the site. Old threads are usually for info only rarely used to ask questions as the folks may not be around anymore. Just sayin..!