hello hesky, i so your post on the sts site.
i hade contact jp about it and they did not reply to me jet.
i have orderd the new long mainfold from jp to see if this works better.
i had no time to test it jet,i have a club race next weekend then i wil test it,
and i have 4 weeks hollyday now jes, time plenty to test it.
i wil keep you informt,how it went.

Hesky/D, i think your guys hit it spot on.

I changed from the JP to my NSR for last weekend's race and had experienced similar probs. So i tuned the NSR back to standarad settings (Cyrul's method) and started from there. The engine was good at idle and top end but had problems with low end just like the JP. So i had suspected the clutch was the root of the problem. Loosen the clutch spring about 0.2mm and t was better but the biggest improvement was when i changed the darn clutch shoe. And presto - the engine came to live and no probs later on.

Now that i have a good clutch going - will try to put the JP back on my car and see how this mother rips!!! will fill you guys in on my quest for 'another happy outing at the track'

Cheers and thanks for all the help guys!!!

Just curious any of you guys run the FX12 5 port with or without the 5.4mm insert that comes with it??

Also, i've ran the engine 25 tanks till today. Should i remove the 0.1mm shim and keep it at factory setting of 0.3mm head shims?

yeah let use know how you get on.

yup, you have to bare in mind with these very revy 2 stroke engines they produce there peak power rather high in the rev range, if the clutch engages to early or drags quite a bit you will get a false impression and think the motor is running out of tune. also you can have the same engine in one car and then put it in another and it may feel like a much quicker or slower engine due to the efficiency of the cars transmission, gearing, clutch set-up, weight, the list goes on!
Its easy to forget about the transmission set-up of the car, I try to make sure the car is running as best it can when I start dialling in a new engine.
Glad your getting somewhere now

Using the 5.4mm insert will increase the usable range of the carb on your 5 port .12. Simply put it will give you a wider window for getting it in tune, making it easier to get dialled in. but at the cost of low end power, it is still a restrictor.
if you are not running more than 20% nitro shimming it to .3mm should be fine. keep an eye on the temp.

Three questions:
1. How do I check head clearance? I think I saw a video on how to do but I can't remember where I saw it.
2. I heard that JP is offering an O.S. line of engines, it this true and when are they coming out?
3. You here having had JP engines, would you recommend getting one, I run mainly club races and have been told that a mod motor is too much engine here. But the top racers that show up from time to time all have mod motors.
thanks

Can't say anything about the new line of JP engines, but it appears that now they want to clear out their old Nova NS based crankcase by still not modifying the new LS from Nova. Since Novarossi's pricing is up every minute, I guest that's the main problem many engine tuner gave up from Novarossi. JP OS TZ based can be interesting, but who knows what they'll do next...

This is the way I do it:
cut a 6" piece of solder (pretty thin solder)
bend it at 45 degrees about 1cm from the end
pull out the glow plug
inset the bent end of the solder in the glow hole
make sure the bent end of the solder is butted up to the inside of the sleeve
rotate the piston past tdc, you will feel it getting tight as the piston flattens the solder
pull the solder out and measure the squashed end with a vernier.
that will be your head clearance.

Hesky, how do you mean "bent end butted against the inside of the sleeve". do you think you can get a picture of how you do it?

Just make sure you get a good bit of the solder under the flat part of the head button, like this pic shows..

good old microsoft paint

Edit: use pretty thin solder also, you'll only be measuring 0.5mm at most.

LOL...that's pretty awesome. I would have never thought to use paint. I would have overcomplicated things with Photoshop or Fireworks or something

hello hesky,do you need to take the rings out ,the ones under the head button,if you want to messeur the head clearens,with solder?

what ya talkin about its much more complicated than CAD or solidworks, its what all the pros use when they need a powerful convenient computer aided design suite


rings? you mean head shims right?

sorry i meen the head shims,excuse me.
do you need to thake the shims out or not?

no, you want to have the engine assembled with the the shims, and verify the clearance is correct once the engine is about to go in your car. or its just a simple way of checkin an engines head clearance without takin it to bits.

What should I do if the engine become dead AFTER medium burst of full throttle. For examples, I give full throttle for 2 second acceleration, let go the gas for a corner, exit that corner and full throttle again but.... flame out.

Currently my engine is screaming little bit on the rich side at top speed ( the scream is not high pitch as usual.... little bit rattling sound ).

Is it the compression things ? Is it too rich ? What is probable cause if it still dies after I lean it ? Thx for your inputs !!