Forum

[Alan R]

Hello again -- Yes, I'm with LES H, and BULLET WHISPERER on this one. Starting with a BOG-STANDARD Bullet 65 as purchased the 17T sprocket is generally regarded as too low, so an 18T fitted can now be taken as the basic "starting point" if you like. Based on that idea then your 19T sprocket is the first GEARING upgrade to be considered---you've already done this and, as LES H says---it's a messy and expensive job. Save yourself a lot of grief (not to mention MONEY !!!!) and leave the 19T sprocket where it is. Get both the jetting AND timing sorted out now. At this stage I would leave the slide alone for now. A "richer" slide refers to the initial throttle response when being first opened from idling. This is NOT your problem area --yet! Incidentally you still haven't told us what air filter system you have ?? Have a re-read of your first posting---- you are actually half-way to your original intentions. The problem is at the upper end of the performance band--ie the MAIN JET allied to the timing required for that scenario. SO what to do then ?? Leave all that you have done so far alone-----try a 120 main, then the 1mm drill (130 equivalent) if needed. You don't have to even remove the carb. for this---just slacken the clips and rotate until you can remove the float bowl, AND as LES H says---check the ignition timing is correct ----. Finally, put the needle back to the No3 position. NOW take it for a test run and see what the plug is telling you. Handy Engineering Tip No.1----Absorb the Guinness AFTER a successful trial run, NOT before. The eyes & brain stay clear--as does your licence of any points. LoL !!

[Al]

Hi Les H. Thanks for your concern. You're right. I should define the ignition now, maybe pop in a bigger main jet. No expenditure yet, so we'll give it a lash over w/e and see how she blows. Sometimes the best action is in-action.

[Al]

Les, you're absolutely right. I should chill out, no rush. Do the simple first things first; then down the pub and watch the rugby, check the Guinness is up to scratch. Cheers

[Al]

Les, you sre absolutely right; keep it simple if you can, do the obvious first. Then I can get down the pub and watch the rugby on sky. And check the Guinness is up to scratch. Cheers.

[Al]

WOW, I've just discovered that this has rolled over to page 2 on the thread. I'm so impressed by the continued direct supply of experience and advice from you guys. Allan, your last instruction is detailed and superb. I'll do precisely that. I knew it was ill-advized to change more than one thing at a time, as you said. There does seem to be slightly different opinions about 18 or 19. I'll leave that as is for now then, as you say. I've got a 130 jet as well, let you know tommorow how I get on. Air system is standard. I have an S&B filter, that was part of the plan, but hitchcocks suggested the extra air was exaserbating the weak mixture so i reverted to std to see.

[John L]

Al -
I second the advice given by Les H.
Plus the following thoughts re your original posting:-
"The intention was a good cruising speed without flogging the engine". Sounds like you're doing exactly that with a 19t. sprocket that the engine can't pull.
"Massive pre-ignition, horrible metallic rattle and engine failure/cut-out" - suggests to me you've already suffered a partial seizure. Check the compression with a reliable gauge; is the engine now running more noisily than previously?
(Any further attempts to "tune" this engine will be ultimately wasted if it's already suffered internal mechanical damage, of course...........)
How was the increase in C.R. achieved, and how was it measured ? And was it measured, or simply guessed ?
This increase would almost certainly require you to retard the ignition timing, and also possibly change the grade of spark plug - have you done either ?
I also have doubts that you have a truly free-flowing exhaust - simply knocking out a baffle may not achieve it. Have you checked the downpipe for restriction and removed it (if found)?
Carry out changes one at a time (or as few as is practical) to enable you to assess the effect of each and verify that you are moving in the correct direction.
(That may now be very difficult).
Have you noticed I haven't even mentioned carburation ?

[simon]

Mmm it's true what they say I had to dial back my advance to 7/16" btdc rather than the original 1/2" once I'd raised the comp to 8:1.