Where has the speed gone

Hello Everybody.

I have a small problem that I’m hoping somebody can help me with. I have a PX200EFL with a 210 malossi kit and supposedly a t5 4th standard 24mm card and sip R/H pipe the scooter has been dyno’ed and was 19.3 BHP and was rejetted correctly at the same time so I don’t think it’s a carb issue but I could be wrong. My problem is top end speed or the lack of it in my case. You see I can only get 65 MPH which is a bit of a pisser really considering and I was hoping somebody out there could help me get a better cruising speed maybe 70/75. Acceleration is not an issue as I do a lot of two up riding and I’m not really concerned about it but I’m sure I should be getting better speeds than 65 when 2 up. The main problem is 4th gear I can get 60 in third 2 up with out a problem but as soon as you put it into top gear it struggles and does not seem to want to go any faster. Even though I was told when I bought the scooter it had a t5 4th in it could it be that it’s not a t5 4th and this is why I,m struggling so much? Also I know it has a kit on but I don’t think it has been matched could this cause the lack of top end. Another thing is the rattling I get when I am at this speed could this be the small end bearings. A lot of questions I know but please somebody help me before I pull the last of my hair out.

Hi Jidoka,

I only know a little but I will try and help.

I will deal with you’re last point first as this could be important.
The noise you describe sounds like pinking a bit like a bag of nails rattling, this is common with the 210 and is usually caused by high compression (running to hot). If you continue to run it like this there is a high chance it will seize, I am taking from bad experience here!
I don’t know what head you are running but if its standard P2 head just opened out at the circumference then you may need to have it modified to lower the compression as well. I had pinking problems with my 210 as well, but managed to stop it with fine attention to jetting, timing and plug. What is the main jet size?

The power problem
I have a similar set up on my 200, only difference is a scorpion pipe and the casings are done.
But I have run the 210 and scorpion on standard unmodified casings and on both the power in 4th didn’t come until 70mph+ and that was with a T5 4th on one of them, although I could rev to 70mph in 3rd!
A 3.00 x 10 on the back brings the power in at about 65mph+ but watch for grounding as the scoot sits a bit lower.
I also tried a smaller clutch drive (20 tooth) this brought the power in at 60mph and am still experimenting with different gearing.
You may find that if this is the problem that you are better off with a sito+(Rust Quickly) or standard exhaust for 2up use. I have used these and although they may not give much more than 75mph top end at least they pull better at low-mid revs.

Good Luck


I would agree that you need to go up one size on the main. I noticed mine was running rich lately, (after much farting about), so decided to reduce main from 122 to 120. However I didn’t have a 120 handy so put a 118 in and it goes like a thing that goes very fast but it has started getting a bit strokey and the plug is bright ginger! it’s not a prob for me as most of my riding is short round town trips but I will defo upjet for Kelsoe.

Hi Jidoka, I have run many Malossi kits and am not aware of a ‚rattle‘ common to them. If your engine is producing 19bhp then I wouldnt think you are to far off optimum set-up, especially on the 24si carb. Id be interested to know where the power comes in on your dyno curve. Then you should be able to work thru the problem. From what youve said, I would re-check a few things, Squish clearance, what plug youre running,B8ES? what timing figures and re-start from there. If Vespadoc is about have a word or email him direct off the profile. Im not a great fan of the sip/lomas pipe along with many on this forum, but I wouldnt be would I. But is it a stainless pipe? It makes a massive difference. It would be worth double checking for the t5 4th aswell.

Hi Mark

As i said before the scooter was set up on a dyno and rejetted by reedspeed. The main jet is a 128 the head is a Taffspeed modified one (sorry should of mentioned that). I have had the scooter for about 9 month and have alyways had this rattling noise it males no differance if i’m 2 up or solo the noise will only start at 65 mph if i drop to 60 it stops. I have done a lot of motorway riding and have riden with the noise constantly and i’ve never had any problem with seizing. When i took it to the shop to be dyno’ed i was told the rattling was a comon fault with the kits and not to worry about but it’s getting on my nerves now and a lot of my freinds who have the same kit don’t have this problem.


on two engines that ive built the owners saw fit to have them dyno’d both at reedspeed.both of them were told to reduce main jet by one size to what i’d fitted.both complained of pinking afterwards.both returned to my original jet size.both were cured.dyno tests will show you the optimum power you can obtain with your motor.in order for the graph to be pleasing to you the owner it has to read maximum hp.this is achieved by a slightly lean mix which will make it fly a tad bigger.bear in mind it gets thrashed for a few minutes on the spot.when you ride it it gets hotter longer so needs to be richer,hence go up on the main jet.secondly,forget shop bought expansions and give the beerace a bell


The information sounds good to me what jet would you advise me to use? and would it give me that little extra speed i’m looking for? Also do you think i could cure the rattling if i got some jap small end bearings from taffs


Hi Jidoka

Sounds like it should be set up allright especially with taffs head, you could maybe try a bigger main jet just in case. Sorry I don’t know what else it could be as I guess the small end would rattle at any revs.
Also if it’s making 19+bhp then its likely that the casings and crank have been altered.