Hp4 flywheel,Any good?

Are the lightened flywheels a worthwhile investment to help bridge that 3rd/4th shortfall on a p210,t5 4th,scorpion,26mm carb?

it felt slight (I think you are meaning T5 4th felt just slightly longer then needed) but is not that slight, you need to bridge about 1500rpm and it is not that slight as far as gearing concern.

The Hp4s bring the power in too fiercely like a motor crosser. The sound and wheelies are awsome! The wrecked clutches are a pain in the arse. Most dealers charge around £80 for a std cosa clutch. If your gona be a hooligan on it its wise to have a band welded around the basket as they can spread at high revs. Also I drill holes between the rivets on the baskets and weld them up to stop the rivits shearing(did this on the way to Whitby in the snow this year!). If you havn’t already bought a flywheel the pk one is defo a better option as Curare says. Also get strengthened springs- the worb5 ones are ace as are taffys. This is a pain now but ensures a long lasting motor.
Good luck with it mate

Scoot basically feels like if it could hit that power band in 4th it would fly but I am a big guy so that doesn`t help,so the jl should help over the scorpion and if I change the gearing and flywheel as well???[:dance1:]

Many thanks,so is the t5 4th already 65 tooth?

Curare is right about the jl right hand exhaust. The scorpian is brill for high reving motors but you need lots of torque to get there. The pm is also very good.

Thanks,I put it on the dyno at the shires and it pulled 82mph/17.5bhp,the dyno guy said the carb setup was ok but suggested that I may benefit from a jl exhaust over the scorpion(cos I already have the scorpion I was asking about de-restricting it but it seems that as the front down pipe is clear it is not an issue),which you have just reitterated,so I reckon this and the hp4 will be my next move.Should I adjust the timing?

if you go for the option of a lower gear ratio I would keep the Scorpion. It gives you more power at higher rev then the JL. The problem as you have experienced is getting to this higher rev. With lower gearing you will get there.

Try 21/65 so you will need to change just on the clutch side.

The Stoffi head you could buy on the net at Stoffi’s garage, try to find the address I don’t remember it.

It is a p2 disc,so we should opt for standard primary,existing t5 4th and just change the clutch gear to a 21?Think i`ve got it.

Should I just opt for the JL and bring the rev range down?Which gives more bangs per buck as I would have to pay my local dealer to do the gearing?

Thanks guys I think that`s what i will do,probably couple it up with the flywheel and a new head!Like you say it gives me more options with the 22 if needed.Will the 21 make a big change as tthe t5 4th seemed slight?

ok, I understand…
21/65 then it will give you a more noticeble difference.

Just to tell you all the story about HP flywheel. They are clutch killer. If you don’t mind changing clutch no problem. They tend to be more mecchanically noisy. If you don’t mind this that’s is ok then.
But if this two last things could be a problem get a PK flywheel modified for PX instead.

Sold to the man with the P2!Why do they kill the clutch,due to overrevving?Reckon I will give the fly a miss then!
Well faint heart never won fair lady so 21/65 it is.Is the 21 a stock item that your local dealer may have,or specialist like taff`s or reedspeed?
Many thanks for the advice guys,definitely pointed me in the right direction.

it would help a little. It will give you a little more power in the „black“ zone.
The better exhaust for this tuning are the JL right hand and the JL RZ2000 if you want it left. Scorpion is great for more hard core tuning.

The best way to cure this problem is to down gear. Use 68 tooth primary and 21 tooth clutch gear. My 210 pulls a genuine 85mph at 9200 revs. This is on a reedvalve but i have just built a motor with std carb which pulls 70 into a headwind. This is the same gearing as an up geared t5 sorry dont worry about overreving. The lightened flywheels are good and do add power but could make the problem worse due to the reduced throw of the engine ie its momentum. Also the screws that hold the fan to the flywheel should be thread locked as the fan can part company with the flywheel.


you have asked if you should adjust the timing. This depends how is the timing set now.
A good set for the malossi is 17.
Try to use the less advanced timing as possible without loosing performance. In case you have some little problem at low rev you could always use next hotter spark plug grade, but the bad effect of a too mutch advanced timing can’t be mitigated.
The less advanced the timing the best the heat will be transfered to the gas and as consequence the barrell will be cooler and the gas, beeing hotter will travell faster using better the expansion.

If you don’t mind staying high on the rev you could always consider Diablo advice to use shorter gear ratio.

And don’t underestimate the use of the correct head. There are big differences between differents machined heads.

then as you say mmmmmm…
try a Stoffi one modified for Malossi. It is good with the malossi standard stroke.
It won’t cure your problem, but your engine will improve, and this is not a bad thing.

I have to say I am not sure 21/65 works. I know it fits but have recently seen an engine where somebody had done this and it had a lot of damage to the clutch cog and primary gear. Ive yet to see a 210 without a 60mm crank that will pull 4th in all conditions using 23/65. The power band on a malossi is so high up the rev range you only get into it on the flat or down a hill. 70mph in third 50 in 4th! If you really dont want to down gear primarys Harry Barlow does a 37 tooth 4th gear (T5 is 36). They work well but are still untested long term.

No,what I mean is that when I had the t5 4th gear put in,the differance between it and the standard gear felt slight(not a lot of differance)so I was asking if the 21 will make a big differance?

Hi Curare seems to have better knowledge of this than I do so I would say try it. I have to say Ive never seen damage to clutch gear or primarys with other combinations but im often wrong. Try ringing a few dealers who are tuning fast vespas especially Taffspeed and see what they say. If you down gear though forget about the lightened flywheel as you will start getting clutch problems.