ESE's works engine tuner

[TZ350]

Attachment 290611
Still a rough spot at 7000rpm, but likely to be exhaust length.

I was impressed with your bike, it was very well put together.

A small adjustment to the exhaust length to see if it can be better balanced with the inlet tract is certainly worth a look, it will only be a matter of a few millimeters.

The air correction jet may be worth a look to, the rough spot was not so evident with the leaner main jets.

originaly posted by Husaburg

A smaller air correction jet will not lean the main out as much at the top end of the rpm range. So by fiddling the air correction and main jet you may be able to lean the bottom off and keep the top rich.

[Bert]

Attachment 290611

Great dyno session on the FXR/FZR tonight. Mikuni TM33, Ross racing Piston and Kelford cams. Still a rough spot at 7000rpm, but likely to be exhaust length. 71 runs on the Dyno with a very patient Rob.

A small adjustment to the exhaust length to see if it can be better balanced with the inlet tract is certainly worth a look, it will only be a matter of a few millimeters.

The air correction jet may be worth a look to, the rough spot was not so evident with the leaner main jet.

A smaller air correction jet will not lean the main out as much at the top end of the rpm range. So by fiddling the air correction and main jet you may be able to lean the bottom off and keep the top rich.

two cents for consideration.

Close, but looks rich on the pilot circuit, transfer onto the needle (~6.5k) seems to flood things then likely a little lean on WOT.
Try smaller pilot, slightly thicker needle and keep the main (go up if a size when hole is filled). I don't think dropping the needle will resolve that hole. Refine with the air circuit (just don't starve it at the bottom end).

[husaberg]

two cents for consideration.

Close, but looks rich on the pilot circuit, transfer onto the needle (~6.5k) seems to flood things then likely a little lean on WOT.
Try smaller pilot, slightly thicker needle and keep the main (go up if a size when hole is filled). I don't think dropping the needle will resolve that hole. Refine with the air circuit (just don't starve it at the bottom end).

Its a foul stroke guys leave it alone.
best bit of carb advice is you are both right, as they have overlapping circuits. personally that's why EI and similar carbs are intersting, because they don't.

this is one of the best bits i have seen.Cameron
http://books.google.co.nz/books?id=J...ameron&f=false

[Frits Overmars]

Frits, somtimes a balance shaft is a necessity, I would be frightened to even get off the ground with this engine before the balance shaft was fitted, now I'd be happy to fly all day.

Neil, I am very much in favour of a balance shaft for almost any engine, regardless of cylinder capacity. What I was trying to say was:
If you just drive the balance shaft from the crankshaft, the gear friction will consume about 5% of the power needed to drive the balance shaft.
If you use the balance shaft as a counter shaft, that gear friction will consume about 5% of the total engine power.

[mr bucketracer]

Attachment 290611

Great dyno session on the FXR/FZR tonight. Mikuni TM33, Ross racing Piston and Kelford cams. Still a rough spot at 7000rpm, but likely to be exhaust length. 71 runs on the Dyno with a very patient Rob.

i would try a oko 30mm carb for starters . around a 118 jet , drop the needle one from centre , think your will a better base run before going to big in the carb, not a bad run anyway

[Flettner]

Frits, I might just have to suffer that loss, the reason for running the engine in reverse is handling related not engine related. The reverse cylinder is because I'm sick of dents in my chamber ( not put there by me I might add! ). The difference of 3 - 4 HP at around 70 - 75 total in an off road bike probably won't be noticed, well, certainly I can't use all that.

[richban]

Attachment 290611

Still a rough spot at 7000rpm, but likely to be exhaust length. 71 runs on the Dyno with a very patient Rob.

That looks like your classic reversion hole at 7k for sure. I would be looking at the muffler more than length. Looks almost like it has some sort of reduction in the muffler. Or its a megaphone? I have sean plenty of graphs like that trying different exhausts on FXRs.

[Flettner]

Sand cores multipling in Claire's oven, as time permits, during the day when she is at work.
Copied the bondi fill transfer core box into metal at the foundry this week end, so now I can make hot sand cores. If I was interested in production I would have made a few more metal die copies but I probably will only ever need 12 transfer sand cores? One casting to machine up first and make mistakes on and the second "real" one.

[Yow Ling]

Was given the job of custodian of this engine, aircooled rg125, it was built by Pete Jones, has run but needs some loving.
Should push all your aircooling buttons TZ. The cooling fins that look like the head are just cooling fins attached to the head beneath.

[Yow Ling]

Sand cores multipling in Claire's oven, as time permits, during the day when she is at work.
Copied the bondi fill transfer core box into metal at the foundry this week end, so now I can make hot sand cores. If I was interested in production I would have made a few more metal die copies but I probably will only ever need 12 transfer sand cores? One casting to machine up first and make mistakes on and the second "real" one.

So you going to make a twin? the pipes will be like octopus tentacles. Does the crecy engine like expansion chambers as the RR version only had stubs

[Flettner]

No, just a single, always a mistake will be made on the first casting!
Crecy was supercharged so it's quite a different engine. I'm just stealing the open ended sleeve tech, I'm not even using their sleeve drive.

[TZ350]

aircooled rg125, it was built by Pete Jones, has run ...

I like it, I have some heavy industrial heat sinks that I am interested in using, thinking of air cooling a RGV250 cylinder that I have had the cases for, for some time. I was going to make a H2O 100 but an air cooled 125 has its appeal.



Just about figured out how to get the heat from the exhaust port area out to the fins. The current idea, is to fill the water cavity with copper wire off cuts and oil and sandwich the cylinder between copper faced heat sinks.



Using an RGV250 cylinder would give me a power valve and a great cylinder with open access to the transfer ports for fuel injecting.

The EFI thing is part of getting these air cooled projects reliable.

And there is an even more challenging but exciting follow on project in the wings, so plenty to do.

[Nickko]

That looks like your classic reversion hole at 7k for sure. I would be looking at the muffler more than length. Looks almost like it has some sort of reduction in the muffler. Or its a megaphone? I have sean plenty of graphs like that trying different exhausts on FXRs.

Thanks Rich, the muffler is a CRF250 - straight through.

[richban]

Thanks Rich, the muffler is a CRF250 - straight through.

Cool. Have you ever had it apart? I had a Yohsi pipe that was straight through. But it had a little ring in the middle to push air around into the second perf. I removed the ring and the second perf and what do you know. No more reversion hole. Also you could try dropping the bottom of the Header 2-3mm from the bottom of the port (mismatch the port to header). I have also done this and it seams to be an improvement. Leave top and sides of the pipe flush or a tiny bit bigger than the exhaust port. Or of course it could be something different. my 2 cents.

[speedpro]

Does that apply to smaller engines as well?