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Best Pipe & Carb to run on my Yam Jog Malossi 88CC Big Bore Stroker??

T

TwisttheGrip

Well-Known Member
Greetings,
Great website you have.
I am Scott, and am building a Jog/Minarelli style Malossi big Bore 90cc liquid with 45MM crank. (converting a 50cc air cooled motor to water cooled 88cc) My use will be street riding/commuting and no racing.
My choice between Pipes seems to be
Mallosi Exhaust Race pipe for Big bore 90cc (Malossi
pt. # 3213751) Designed for Yam Aerox,
This is the only Pipe I have heard of that is specially made for 90CC and it is a new Pipe in Malossis pipe lineup as it was recently introduced a year or so ago.

or

Yasunni Carerra 30?????

I heard the Mallosi pipe is made for 90cc, but the Carerra 30 is made for 70cc, but it is too big for 70cc, so it will work better than the Malossi as it will give a broader power rande at the expense of less peak power. This guy said build quality is also way better on Yasunni.
Another friend said Yasunni may be better as they only make pipes.

Both pipes above are Obscenely Expensive!!, but may be worth it??
I believe these are the only two that will work well with the big bore stroker motor??


Does Yasunni have a USA technical help line??

What carb would Ii use and how big MM??
My friend suggested I use the Arreche 21MM and said the Arreche 24MM is too big, plus the round Arreche airbox only fits up to the 21mm carb.

My quad racer friend uses a OKO 30mm, but that is dirt racing and different than scootering says my other friend. My motor will be built mini quad racing style, so our motors will be nearly the same except the quad pipe is also different????
My guy said 70cc mhr racing used 19MM, so 21MM shoud be fine for 90cc???

All yoou racers/speed guys who have built this same motor please help out and advise and thanks so much for all of your priceless knowledge, you guys are great.

If you have any other suggestions for my project/motor build, please feel free to advise me.

Regards,
Thanks,
Scott
 
bad choice of crankshaft for the MHR BB 86cc kit, 45mm stroke will make the port timings too high, get a 44mm crankshaft to bring the timings back to spec so the engine won't be peaky which is bad for street use.

the Yasuni C30 is a poor choice for a pipe, it's a very high revving pipe made for tuned 70cc kits, not for a big bore & long stroke setup like an MHR 86cc kit which makes power & torque at lower rpm.

just get a malossi big bore pipe or a roost custom pipe.

24mm is fine for 86cc if you're going to use it mainly for the street.
 
Thank you so so so Much True Overrev and Tiba karotsu,
I have been waiting for this info for a long long time with no luck until I found you Great Speed People--You are Truly The Best!!

Where can I buy a Roost Custom 90cc pipe/in USA??????
Where is best deal on Roost?????
Are you sure this will bolt onto a Yamaha Jog??
I guess if it needs slight modifictions it is OK.
Can I get Pipe in Nickel or Chrome??, or is it made of stainless Steel?????
I guess i can always plate it myself later--

Where is best place deal to buy Genuine PwK 24mm carb?????
What do you mean Genuine, just Keihin PWK or are there counterfeit Keihin carbs out there, or do you just mean do not buy another brand 24mm, only buy Keihin PWK???

My Hawaiin Scooter Guru who I love said Areche 21MM will work fine for this setup, even though it seems a bit small, but big advantage with 21MM Areche is Areche makes an Airbox to make the Intake Noise less noisy etc.
But I know you are probably right and 24MM PWK Keihin works best, But can anyone please tell me if it is possible to buy an Custom airbox that will work with this 24MM keihin carb so it will be quieter and more resistant to water and dirt????

My Quad race guy who will build my Motor uses his own single ring custom piston (like a piston from a Dirtbike etc) with the Mallosi kit/therefore he does not use the MHR Piston with 13mm pin that comes with kit for the 86cc stroker motor, and the timing works out fine. The advantage to this is he uses a cheap Quad 45mm stock crank or generic 90cc full circle crank instead of the expensive Overpriced $800 Malossi 44mm crank.

Sorry for all the questions, and thanks so so so much.
I will search the web for Roost while I wait for your great replies.
Thanks so much Tiba and True.
You guys are The Best.
 
you don't need to buy the expensive malossi crank, stage 6 makes a 44mm crank for less than half of what malossi stroker crank sells for & performs just as good & is superior that oem quad cranks in terms of quality.

just get a Keihin PE24 carb & custom fabricate your own airbox or you can use your existing airbox & find a hose that will connect to teh carb from the airbox.

to fit the 86cc kit & crank you will need the crankcase bored to make it accept the bigger cylindr & crankshaft.
 
True OverRev & Tiba,
Sorry for so many Questions and being so picky.
Thanks, True, you mentioned "Genuine PWK 24mm" but I talked with keihin, and they do not make a PWK 24mm, and they said they are all Fakes.
The smallest PWK carb they make is a PWK 28 mm. Is this too Big????
I can get a fake Chinese PWK24 like for the MiniQuads, or Mikuni makes a Genuine Mikuni flat slide 24mm also, or I can run a Stage 6 24mm (probably Keihin pwk copy)carb, or like Tiba said just run the keihin round slide PE 24mm????
So many choices what do you think, should i run the more modern PWK style carb or the older syle PE round slide carb???????
I do believe you about 24mm, because by the math 24mm seems perfect as my Guru uses 19mm Areche for 70cc, and Pwk33 for 120cc, so 90cc = 24mm
But Ironically my Guru recommended Areche 21mm for this big bore setup.
also my Quad racing friend uses OKO 30mm for same motor setup (so 21mm seemed too small) I will be using, but Quad exhaust is different than scooter, and everyone seems to think the 30mm is overkill for him;therefore in light of all this info 24mm i always thought was the right size, and you guys do also, but now PWK does not make this size, at least in genuine PWK.
also I amnot sure whether i will use a 45mm crank for 88cc or 44 crank for 86cc, just to let you know displacement.

I am off on my Carb and parts hunt.
Sorry for so many questions and being so picky.

Thanks so much you guys,
You are Great!!
 
Last edited:
for the MHR BB 86cc use the 44mm crank, using the 45mm crank will throw off teh port timings & make the engine nearly impossible to tune. the engineers at Malossi probably know more about their own product than everyone else.
 
Round slide vs flat slide style carbs?

Yes you are correct Tiba,
But my guy uses a custom piston/like from a different Dirtbike/like CR85 Honda that makes port timings basically the same,
But I think I will go with the Stage 6 copy crank so i can use the piston that comes with the Kit.
Thanks

Tiba, I researched the PE 24 carb VS Pwk 24 carb,
Keihin never made a pwk 24, but plenty make good copies like OKO and mikuni, but that is not my question,
and although the more modern Pwk flat slide style is supposed to work better, one racer told me to go with the PE round style carb as he said it runs better as it never stumbles at a certain point in RPM range and he said the PWK style will stumble and sometimes cannot be tuned perfectly like the Round style carbs can????
Please confirm or deny about Round VS flat slide carbs.

And Stage 6 cranks seem to be now way more than half cost ao mallosis, so
Where do you get good deals on Stage 6 cranks????
I am told $500 USD for Stage 6 crank coming from Canada.
Thanks
 
The piston does not set the timimg ,the stroke sets the timing
You can put in a different piston but by the time you set your squish you will be back to where you were
 
Block Boring etc?

Tiba an others,
Tiba said,
"to fit the 86cc kit & crank you will need the crankcase bored to make it accept the bigger cylindr & crankshaft. "

I am told that with the Stage 6 or Kieser 44mm scooter Cranks, the block/case only need to be bored to fit the Cylinder, but the part of cases tht hold crank does not need boring as the crank fits like the 50cc crank. Is this true???
And I am told by a couple of you that Keiser and Stage-6 are comparable/same in quality??? But am told if i go with stage-6 I need to get R/T Crank and not Replica.
I am told Kierer makes tow versions/12mm and 13mm pin, but do they/keiser make a race and replica crank ??????? also cause i don't want to buy the non race one and I ask cause I recently learned from you that stage-6 makes a non race crank also.
On similar subject I also heard Roost makes two versions of the 86cc big bore scooter pipe, one for lower RPM and one for higher Rev, but the website only shows one version??
I believe my setup would require the lower Rpm Version/more torque version???
Does anyone prefer Stage 6 over kieser or vese-versa??????
I can't find the website for Kieser or 2-Fast??

I am told to buy Stage 6 scooter/backdraft style (not sideways like Quads) intake for the 24mm PWK and Kosso Reeds?????

I know a 45mm quad crank need to be bored for both the cyl and crank, but I am going with one of the 44mm cranks, so port timing correct and less boring costs.

My goal is to build fast yet reliable yet torque type scooter that can handle big hills in the heat and that is why i plan to build 86cc LC MHR with roost pipe instead of more simple MHR 70cc air cooled setup.
The 70cc is far easier and smater/bolt on (platform MHR racing famous for 70cc), yet i think the LC 86cc will go faster up big long hot hills with more reliability????
Please correct me if i am wrong cause i would hate it if 70cc passes me up the big hills???

Thanks as always
 
the 44mm stroker crank on our 2Fast kit didn't fit our Jog carters, the crank well had to be bored to accept the bigger diameter crankshaft, the longest stroke we used without boring the stock crank well is 42mm, more than that & the crank well needs boring.

of course the 86cc should make more torque & power at a more accessible (lower) rpm so it should leave the 70cc kits in the dust especially when you go uphill, the results vary depending on how skilled the tuner is. the one with the more intimate knowledge of tuning will be able to squeeze out more power than your average mechanic or enthusiast.
 
 

thanks for chiming in Billy.

Twist, you should definitely listen to this guy.
 
I have heard that js80 tubes will provide more horsepower than the roost pipe for malossi big bore 86cc? someone who has tested the new js90 exhaust pipe?
 
Which Gears Brands and Ratios Best?

My 88 Mallosi stroke will be used primarily for street, and I wil build this larger liquid motor (instead of AC air cooled 70cc) for torque and hills, and I will use a MZ moskito (Yam Jog copy) 50cc block as my basis, I still need to buy aftermarket gears for this setup, so my question is what gear ratio should I use for the 86cc Version?????
There is only probably a few choices to run

In the event that I use the MZ block and build a Air Cooled 70cc motor, same question as above, what aftermarket gear ratio should I use for 70cc???

I also was told to only run gears from high quality co's like Polini, and to stay away from Taiwan stuff--Is this true, or is there good inexpensive gears?? What is namd of co? where can I buy???

Thanks,
Twist
 
Pipe Conflict with Centerstand/Kickstand Problem

Thanks Billy and Tiba, and True,
I heard that these Big Race Pipes will conflict with the centerstand and you cannot use the kickstand/centerstand on a scoot such as a 2000 Yam Jog with these 88cc Race Pipes??
Is this true? Can the Stand me modified to work around the Pipe??

I will call you Billy, but you had emergency Plant work a few weeks ago and i could not reach you.

thanks much,
Twist
 
You can use a side stand and get a stage 6 paddock stand or just use a car jack like me, side stand looks better too!

(i'm using a c16 on my aerox with a side stand)
 
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