New cylinder

Nov 9, 2018
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So, I would like to get a new cylinder. Any ideas what to get? Are the Chinese ones the Nichi or what? Could use some assistance. Thanks.
 
Well..... So I did some port work on the oem cylinder. It wasent running right, like the beginning of every gear was tough to go through. At high rpm it sounded and had good power. Almost acts like an air leak because it over heats. Did a leak down test and held pressure very well. Then I adjusted the carb every which way possible and then purchased a lectron carb and it did the exact same thing, so now I know it's not the carb. Then I had another cylinder that I bored out myself and as I was finishing it up I dropped it and an intake bolt hole busted off. Now I want to put an oem cylinder on it just to see if it makes a difference. I seen a whole kit on ebay for 250 with a weisco piston so.....
 
You should be able to find a used oem cylinder? Are you running advance timing?
 
No, no advanced timing. Do you think I should try an change it?
Let's look at this from a different angle first.
What pilot jet is in it now?
What needle # and what position is the clip in? Air screw. How many turns out?
Are you running the stock carb?
Have you done any half throttle plug chops?
All the things listed above and the slide control air fuel mixture from idle to 3/4 throttle. After3/4 is the main.

If you are running lean in the middle throttle positions you will have excessive heat and can give you poor performance. Or it can run really good but not for long. Too lean will damage your top end.
 
Well.... after trying every jet I have all the way from stock 230 to 310, as well as the third and second needle clip position on each jet I could not get it to function properly. I got real close and it did ok, but it overheated. My brand new toomy b1 looks like a rainbow and turned almost white by the head. So I decided to get a lectron carb where you don't need to jet. It did the exact same thing.
 
Well.... after trying every jet I have all the way from stock 230 to 310, as well as the third and second needle clip position on each jet I could not get it to function properly. I got real close and it did ok, but it overheated. My brand new toomy b1 looks like a rainbow and turned almost white by the head. So I decided to get a lectron carb where you don't need to jet. It did the exact same thing.
Have you done a leakdown test?
What size carb?
You can always try a stock cylinder?
What does the plug look like?
 
It was a stock 28mm makuni. Now its a 30mm lectron. Yes did leak down test. Holds pressure very well. In the beginning of this thread was the original question. I'm looking to get a new stock cylinder to see if it makes a difference. Can I get a decent one somewhere just for testing purposes? Or are all the after market cylinders Chinese?
 
A used stock cylinder is best.
If an aftermarket one is used. Go over it. Carefully.port chamfered is usually a problem. Check ports for loose casting all threads. And wash good.
 
So today I took the cylinder that i dropped and jb welded the bolt hole that busted off. Rethreaded it with a new bolt and was happy with the results. Anyway, got it all back together and still same issue. Possibly worse than before!! So I've had nothing but issues with this bike since I've had it. With that in mind I think with the new carb and different cylinder and still same issue??? Well the only thing left is electrical. The only thing original on the bike is the CDI box. Just happens to be i have a brand new one in the garge. I swapped them out and it like a monster came out!! All this time an all it was was the CDI box!!
 
So today I took the cylinder that i dropped and jb welded the bolt hole that busted off. Rethreaded it with a new bolt and was happy with the results. Anyway, got it all back together and still same issue. Possibly worse than before!! So I've had nothing but issues with this bike since I've had it. With that in mind I think with the new carb and different cylinder and still same issue??? Well the only thing left is electrical. The only thing original on the bike is the CDI box. Just happens to be i have a brand new one in the garge. I swapped them out and it like a monster came out!! All this time an all it was was the CDI box!![/QUOTE
Good deal:)
Was it the wrong cdi to start with?.
They usually work or they don't
 
Well, I believe its an original 1989 cdi box, believe it or not. Its the only thing left that hasn't been replaced. Just gotta fine tune the new lectron carb now that everything is kosher. What a relief. Been on this thing for too long now. Thanks for all the assistance. Greatly appreciated!!!
 
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