Thoughts , jetting/exhaust

[Mike - - Bristol]

RT195 , 30mm Delorto AS266 ,X7 3rd clip , 50 pilot , 125 main , 40 slide. Static timing at 17.

Started running in with a PM pipe and all was fine when keeping the revs low and being gentle.
Got to about 250 miles and wanted to start opening it out and wasn't sure about the jetting so had a quick dyno run came out with 17bhp but topped out at 54mph. Results showed a little lean low down and slightly rich at the top end. Tried it on the road and flat out 52mph and wouldn't accelerate hard. Felt like it did when it was way too rich.
Spoke to the guy who dyno'd it and he said the exhaust could cause similar problems.
Next took the PM off and put a Clubman on, 64mph but won't rev much over 6,500 revs.
Richend up the lower end and it struggled so this is where I am now.
It runs well enough , rides nicely if you accelerate gently but still holds back if you try and give it everything..... which I tend to do.
I will bee trying to borrow an expansion chamber exhaust to see what happens then. I did wonder if the PM was blocked , it shouldn't be carbon'd up as there is probably less than a couple of thousand miles on it.
Any ideas ? Should it rev higher ? A mate has a similar set up that is good for 70 , where mine seems to struggle up to 64.

[rosscla]

PM is a peaky pipe and tends to need to rev to produce good power.

Which delorto?

What Clubman?

Do you have a filter on the carb?

You don't mention what gearing your running?

[Mike - - Bristol]

Sorry , standard 42mm Clubman , as I said 30mm Delly standard box.

Went out today and up to 50/55 it's fine as long as you don't try and open the throttle full to accelerate.
Doing about 60mph and opened the throttle further it seemed to die , throttled off and it picked up again. Did this a couple of times.

Next I will check fuel flow , and then drop the main jet a little. I also have the offer of an expansion chamber to try from a mates scoot with a very similar set up , his is good for 70+ .

[soosh]

The PM pipe should be fine. I'm assuming the RT is the equivalent of a stage 4 spec? I used to use one on my iron stage 4 and getting it to rev in 4th was no issue and pulled perfectly,mine was a 200 so yours should be the same. What gearing you running? The PM pipe will only be revy if the timings allow it to.

[Mike - - Bristol]

The gearing is standard Li 150 with 15t front sproket.
Next question is how would I check the flow of the PM ? seeing the Clubman is much quicker. Can't be coked up I doubt it has 2,000 miles on it.
It's with the Clubman on it won't rev much past 6.500 rpm , PM was holding it back wouldn't pass 52mph.

[Architecten]

What crank do you have? And how was the barrel set up?

[Mike - - Bristol]

standard Mec Eur crank and the top end is all set to recommended tolerances and leak tested

[Architecten]

58x107? The reason I ask, and you probably know, is that MB recommends 60x110 to give more tolerance when setting allowing the ports to be set for either low down torque or high end revs... (i could be talking b@11@x here though...!) It also gives a massive extra 5cc!!!

Anyway mines set up for low down torque as this suits the riding I do. It's great through the gears and pulls up hills easily. I've got a a 28mm PHBH on mine, in my opinion a 30mm just uses more petrol!!! After much tinkering the scooter is set up really well although it's not been dyno'd. When it was built the ports were 'matched and flowed' and I'm currently running an AF 42mm Clubman. Here's my set up...

Idle 48
Needle X7 2nd clip
AV262
Main 110

If anything it's still a tad rich but I'm happy with that, it's still only got 900miles in the kit.

It sits happily at 60 and I've wrung 65 out of it. I'm happy with this. I'm think of adding a supertourer next year and would expect this to allow the engine to rev out higher at full throttle. But I didn't get the kit for top end speed, there are other better kits for that. I just wanted a kit that was top quality and would be super reliable. It's been both of those things so far....