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135lc 5speed To Fz Spec

msapi

New Member
Hi,

My plan is to change the below with the aim for good pickup and cruising:

1. Yamaha FZ block, cam and valve spring. Any modification needed on the FZ block or piston?
2. Standard head + port and polishing
3. Standard BS25 carb + rejet mainjet and pilotjet
Standard #15 pilot jet and #115 for main jet. If I increase mainjet to #117 and set needle, is it enough?
4. Standard exzos + change to bigger manifold.
What is the standard manifold size? I plan to change to 24mm manifold, as it the smallest size I found. Else I will need to custom make one. Ideal size for my setup?
5. Change sprocket to 15-39 on a 428 chain from the existing is 14-38. Will I still get the same pickup, but with improved top speed?
6. All else maintain as stock including air box + filter and CDI. Rev limit on the V2 cdi is 8500rpm, whereas I understand the FZ cam will go to 9500rpm. If I find the performance at the top end lacking I will proceed to change the CDI later on. Any CDI to recommend?

TQ
 

traxxas-modifier

Super LOLO
Staff member
Hi bro

1.you can change to 150cc fz150i/vixion bore kit
2. each mechanic have different style of porting, if you have budget you can buy the aftermarket big heads
3.i suggest to buy big carb instead,
4. use aftermarket exhaust, you can use existing intake manifold
5. sprocket is trial and error. try all the combinations to check which one fits you
6.any cdi thats designed for sniper is ok. i use rextor cdi
 

nhoj

Super Veteran
Hi bro

1.you can change to 150cc fz150i/vixion bore kit
2. each mechanic have different style of porting, if you have budget you can buy the aftermarket big heads
3.i suggest to buy big carb instead,
4. use aftermarket exhaust, you can use existing intake manifold
5. sprocket is trial and error. try all the combinations to check which one fits you
6.any cdi thats designed for sniper is ok. i use rextor cdi
is it ok to use rextor cdi in daily use sir trax?
 

nhoj

Super Veteran
khet po ba stock engine ko tpos rextor cdi tpos valvespring tpos cluch spring lang papalitan ko. pde po ba ung mga sir? stock engine po ako ehh
 

msapi

New Member
Quick update;

1. Yamaha FZ block, cam and valve spring - DONE.
2. Standard head + port and polishing - DONE
3. Standard BS25 carb - DONE. Main jet changed to #120. Pilot jet remain unchange.
4. Standard exzos + change to bigger manifold - DONE.
5. Change sprocket to 15-39 on a 428 chain from the existing is 14-38. - NOT YET. Still using stock sprocket.
6. All else maintain as stock including air box + filter and CDI.
7. Valve clearance set at 0.10 intake and 0.15 exhaust.

Currently it is still running in, but I've a few question;
1. Engine starts fine, but the lifter/tappets is loud. What is the ideal valve clearance for FZ cam? I will re-adjust after run-in.
2. During 1/2 - 3/4 throttle, there is slight hesitation/jerking on the engine. It's not consistent, but noticable especially when cruising at 60-80km//h. I've not gone any faster so can't really say if there's any issue at full throttle. From first gear to fifth is OK. There's no noticable jerking when going through the gears.
Is there anything else I should do to the carburettor?
I've tried to set air screw to 2, 2 1/2 and 3 turns, but slight jerking is still there.
 

haen

Super Veteran
change that stock cam.. it's useless.. proper cam should easily boost the power up to 18 hp with ease, even with stock head.. clearance 0.10 IN - 0.15 EX
if jerking main jet usually too small, if it goes unsmooth kinda like stuttering with brap brap sound then main jet is too large.. check spark plug color.. white dry lean.. black dry too rich this usually came from porting changes
 

msapi

New Member
haen,
i'm using FZ cam. Checked spark plug and it's whitish. Will try to up the mainjet to #125. What about the pilot jet? It's currently stock at #15. Should I change it to #20?

traxxas,
Is it possible to adjust the needle on the stock BS25 carb?
I can't see any cir-clip on top of the needle jet to disassemble. What I see is a kinda plastic hat on top that is holding it in place.
Do you whether it's possible to disassemble the needle jet?
 
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