I have all stock blaster other than bored sixty over stock pilot and 250 main I have tried tuning every way possible adjusted needle up down if can get it to scream but it seems to be running lean already replaced all seals and gaskets just ordered new reeds one has slight opening temps running aroun 320/360
Throttling and jet issue
- Thread starter Jason370
- Start date
Have you done a leak down test. You may be sucking in unwanted air causing you to be lean. You can fool with the jetting and needle all you want, if you have an air leak you are just chasing your tail.
If your cases are cracked, it could be sucking in air there. That's why you should do a leak test.
Are you using mikuni jets and needle? People have had many problems with off brand jets and especially needles.
Are you using mikuni jets and needle? People have had many problems with off brand jets and especially needles.
The carb boots are also very prone to leaking, especially if tightened more than necessary (5.6 ftlbs I think) also a leak at the exhaust can cause a lean condition. It is necessary to leaktest anytime you have a problem, after any engine work is done, and twice a year as part of maintenance. It can save your engine!
That dealer who told you to richen jetting for a bore is an idiot.
Only mods to the airflow into or out of the engine require rejetting.
I'll send you a message when I get home later w/ leakdown tester info
Only mods to the airflow into or out of the engine require rejetting.
I'll send you a message when I get home later w/ leakdown tester info
You never have to go bigger on the main when you bore a cylinder. You may have to come down. The main jet you're running is too big but you may be compensating for an air leak. 320 – 360 is stupid hot for a stock blaster. You should be running around 230 – 265. I'm thinking air leak, wrong plug, bad ignition.
If it runs better with the lid off, you are probably rich. Normally you would increase the jet 2 sizes (250). A plug chop is the only way to confirm your jetting, but your engine must be leak free first. Temps, elevation, and premix or oil injection can affect which jet you need also.
Once I change the bad crank seal if I run with breather lid off ahold I still tune carb with the stock main(230) or the (250) and I will leave the pilot stock (32.5 or go up to (35) I will have all new gaskets seals and new reeds and did the rings two weeks ago hopefully still good after running warm couple times trying to tune with bad seal the little fork like thing that holds seal in was bent so it aloud my new seal to come out I replaced that also thanks to all will let u all no outcome when new seals get here wensday
