D.DJ

Hey guys, not sure on my current settings, but I have a possible problem.

On start-up everything is fine, though slightly rich and just yucky for the first few seconds, but otherwise a good tune and ready to hit the track.
When I do go out everything is fine, great top end and take off, but after a few laps or after the race (6 mins) I find that the idle speed becomes really low, I mean really low to the point where if it goes any lower it will stall, which it has done before if I dont blip the throttle.
That is how it goes!
It may not be a problem because I think the HSN was still a bit on the rich side, so before I tried to have the carb open enough to compensate for that, but when I go to start it up later once it's cooled down, or just another day, it's quite high. Leaning the LSN only caused it to be too lean.
Hopefully it was because I had the HSN too rich which bummed my low end tuning, but if it isnt, then can anyone share their opinion?

Colt4g63

Did the engine just start doing this? As you have been running this unit for awhile now.

Sounds like a tune issue to me to be honest. May not be getting it warmed up enough... maybe getting it too hot during the race? Maybe could be low on compression and when the engine gets heat it looses its compression causing it to idle down etc..... There are all kinds of things it could be. Very hard for me to diagnose a tuning issue from my computer as im sure you understand, but i will give it by best shot. So when did it start doing this? Also have u tried a fresh plug? How does the compression feel?

D.DJ

Well so far I think it was because the HSN was too rich, causing the rest to follow suit except in the beginning/on startup. it started doing this maybe about a month or so ago. I think the compression is beginning to go as I can easily turn it over by hand, but i can still feel a fair amount of resistance to it. I tuned it up today and it pretty much stayed on until i bumped a corner, then sometimes it would die on me. If a cold startup makes the engine run really high like the idle gap is too large, then i think its time may be starting to come to an end. I still have a spare un-modified P/S set, so that will be my backup. Break that in, then see if im happy with the way it runs on both the modified crank you did, and the stock crank. if im happy with just the modified crank in it, ill leave it at that. If I feel it lacks too much performance, Ill just match the port timings from my current sleeve and "transfer" it to the new sleeve. Im really happy with the way its running now, but hopefully tomorrow will tell me if everything is still ok. thanks for the reply Adam, good to know your keeping a lookout on your engines

I do know that it is definitely not getting too hot as the temps around here are still cold, and Ive only ever seen it peak at 105 degrees celsius. I think it was the tune on the HSN being too rich which messed up everything else, and also maybe a little bit overshimmed (now it has 2 thick shims and 1 thinner one in it and it seems to be right, i think that totals .5mm of shims) otherwise it's still good once it has some heat in it. BTW, im running it on a Dynamite med #7 plug which is really good ATM, i think ive ordered some #5 or 6 plugs from AMain, maybe its in my basket now, cant remember.

Hopefully I will have news on how it performs tomorrow if the rain can be kept at bay!

D.DJ

Ive decided to sell this engine along with the spares I had with it including a new P/S. Going to try out a new engine instead or replacing the P/S, just because plugs are a real pain to get right for this engine. Dynamite #7 seemes fine but a bit too cold for 16%, so a new engine is where Im headed but can't decide between getting the Sirio XXX with 2653 pipe or a Novarossi 353 '08 with 2630 pipe.
XXX is a bit more expensive (50-100) and the 353 I have some local help and availability for it. So Im leaning for the 353, but Ive seen the XXX and its a real screamer!

So which should I get?