Dyno graph before holed piston

[poppygun]

Any thoughts on this dyno print out as told it was safe to do euro on but it did not make it.
holed a 69 mm mb piston in 50 miles and cost me a fortune .Some mates said it was not right
any thoughts thanks
http://www.flickr.com/photos/64393564@N03/9423387016/

[FREAK]

looking at that ide say main jet is way too small ,weak evertime you gun it,
it is neer imposible to get a straight fule air line ,but that one is all over the place
cnly my opinion

[col68]

Any thoughts on this dyno print out as told it was safe to do euro on but it did not make it.
holed a 69 mm mb piston in 50 miles and cost me a fortune .Some mates said it was not right
any thoughts thanks
http://www.flickr.com/photos/64393564@N03/9423387016/

Who did you have dyno your bike ?? and what motor is it and what jetting etc ?? just had both of mine done by alan at diablo and they are spot on !! col

[jonashford]

dynos a useful tool but its no substitute for actual riding your scooter on a road laiden with rally gear, I'd never compare the two

[DigDug]

dynos a useful tool but its no substitute for actual riding your scooter on a road laiden with rally gear, I'd never compare the two

Give me a dyno with a skilled operator anyday.

[Timbo]

Any thoughts on this dyno print out as told it was safe to do euro on but it did not make it.
holed a 69 mm mb piston in 50 miles and cost me a fortune .Some mates said it was not right
any thoughts thanks
http://www.flickr.com/photos/64393564@N03/9423387016/

Who did you have dyno your bike ?? and what motor is it and what jetting etc ?? just had both of mine done by alan at diablo and they are spot on !! col

He did mine and road tested it between each dyno runs......top man...

[Donnie]

dynos a useful tool but its no substitute for actual riding your scooter on a road laiden with rally gear, I'd never compare the two

Give me a dyno with a skilled operator anyday.

Aye, and there's the rub, you need someone that knows what they are doing and not just someone that is tuning the scoot to run good on the dyno, but someone thats dynoing it for real world application.

Unfortunately even the best dyno operator in the world can't account for the numpty factor ie, once it leaves the dyno, it's up to the scooter rider to have some comprehension of how to ride the scooter within its "safe zone" as well as hoping the owner will actually bother their arse to do the standard checks occasionally on the spark plug, oil level, etc etc

[Darrell Taylor]

should have a graph thats tracing a wavy line between 11 and 12 on an air cooled motor ,

the graph shows a line set at 13.5 that the scoot is seeing on a regular basis thru the run ,that is typical of the ratio that 4 strokes like

[poppygun]

my engine setup is a j b built engine with 1500 miles on it but built in 2009 could not fault it in those miles
Race tour 220 kit ,60 mm race tour crank, dev tour,35 mm mikuni, jetting as jb built 290 main,idle-pilot 20 ,needle 57' 2 clip from top,,run open mouth all setup on dyno by jb in oct 2009 A GREAT BUILD AND SETUP .
Wanted to get new piston rings fitted and put filter on and a m-tec retard unit setup. So talked to my local scooter shop with a dyno. said no problem bring it in .Visit one he fitted rings left sqwishs? at 0.82 i queried this by saying
it should by over 1mm he said it was border line .1ST RED FLAG .Asked about RE torque head after 500 miles to be advised he dose no use one but dose them up tight 2nd RED FLAG. He did say the barrel had some wear so i asked about a replate and he said should be ok piston rings had correct gap.Then do the timing m-tec setting on max F i think.23 to 16 degrees at 7800 revs seemed to work
Next the jetting and filter only had jets down to 250, needle changed to 58 top clip but he said still very rich so advised to get more jets and come back in a week .2nd visit advised him on way over the revs would no drop straight away like a air leek
ok lets sort it on dyno. 2nd time drop main to 200 still rich smallest i have is a 180 drop to that
still a bit rich??????? and holding onto revs still so adjusts air scew ? and says he cured it take for test ride seems great
ride home 20 miles
do plug check on old plug still a bit black think it looks ok should of used a new plug to get a better reading .Do about another 15 miles seems ok.
so start to load up scoot for avignon set off light as mates in van taking gear about 30 miles bang.
Doing ABOUT 60 MPH . Rang MY local scooter shop to be told yes i did think you had a air leak .First vist £120 i gave him £140 Second visit £30 .so far he,s blamed the barrel wear and mikuni carbs they have no adjustment. Also said the bottom end can be cleaned and no need for a strip down seems risky to my £400 crank SO I LEFT THE SHOP .i think dropping jets from 290 to a 180 was the problem and a crap air fuel gauge on dyno , to get back on the road cost me over £500 plus £170 paid to him do you think it is fair that i ask for the £170 back plus £29 for piston rings .this local shop is a scooter shop and lambretta racer been in business for over 25 years so i thought he knew what he was doing also he had know idea about mikuni carbs as well .l repeatedly ask if this is a safe set up to be told yes it would be safe
your thoughts would appreciated

[vespanic]

I'm no expert with carbs but dropping main jet from 290 to 180 in a well set up engine seems to be a big no even with the added air filter.