70cc e50 not revving out?

Hey guys, a few weeks ago I had made a thread about not hitting top speed - I convinced myself things were running right until I rode my roommates freshly built e50 and almost popped a wheelie the powerband hit so hard. Here are the setups:

Me:

- Treats 70cc piston port kit

- Touring head for treats kit

- Mikuni vm20 with 117.5 main jet

- Timing at 17 btdc

- Cylinder spaced with 2 thick black base gaskets and one thin green (3 total)

- proma circuit pipe

- 17x45

- Temps under 370

Him:

- Airsal 65cc kit

- touring head for airsal kits

- Mikuni vm20 with 125 main jet

- proma circuit pipe

- 14x45

On a straight, I was full throttle at 37-38 while he cruised by me at 40+ with much different gearing. Basically, I'm still having the same issue where I don't rev out/hit the powerband. My top speed at 75% thottle is the same as WOT. My powerband barely hits. I have read that squish isn't perfect out of the box on this kit, so I just added some base gaskets and now the piston goes slightly under the exhaust port at BDC. Before today, I had the same setup except for 1 thick base gasket rather than 3, and the hi hi comp o-ring head. It seemed to have muchhhh better lowend, but the top end was the same (not revving out).

I've bought a new carb (had a bing clone 15 before) bought a new head, moved my needle clip, and messed with the main jet. I've read that kitted vm20's are running 130-170 main jets, and 117.5 is the lowest I currently have. Regardless, I should be hitting some form of powerband.

Any ideas?

Re: 70cc e50 not revving out?

Brandon Weiss (Detective brandon to you) /

Are you absolutely sure you set your timing correctly? Exactly how did you determine your current timing?

Also, what's the history of the engine? Has it been rebuilt with fresh seals and a roller crank?

A video of the bike idling, running and riding would be helpful to diagnose your issues. Could be as simple as having your jetting off. I don't use VM or mikuni carbs in general so I cant help much there.

Also, just to be sure, make sure your brakes aren't dragging. (edited)

Re: 70cc e50 not revving out?

I rebuilt the whole motor myself last fall. Stuffed crank, new seals and bearings, new everything.

I set my timing using a timing light. I will recheck it this weekend but I set to 17* btdc.

I've dumped close to $250-300 into diagnosing this issue so I'm pretty frustrated as I feel live I've tried everything. I will get a video this weekend of it running and idling. It sounds like it runs rich in general, at any power point (idle, takeoff, top end). I have a temp gauge so not concerned I'll seize it, maybe I need to try a 100 jet? Seems so far from the 140-180 people are using with a 70cc kit

Re: 70cc e50 not revving out?

Overpriced Parts /

Yeah the Kstar kit basically sucks unless you could base space it up 3 mm and deck/take down cylinder 3 mm,

The Mikuni carburetor, most people do not know how to tune it in, even experts on a piston port moped kit, I once made $200 to tune one in in and once I put a 14 mm bing in its place and put the side cover on and I gave it up only charged 65 bucks and from a friend of mine gave me $100 because the bike blasted, after eight years still runs today, with stock crank stock ingation stock everything,

I’ve been dealing with Mikuni‘s on Japanese Enduro bikes for 44 years on enduros and someon mopeds,

Most on kitted mopeds are only 3/4 tuned in so I don’t recommend any of them on a puch except for the 24tm flat side on a 74 cc or polini reed kit puch or tomos reed kit,

Get a Cheap 70cc dmp pp kit (at dos cycles) on a 14 mm bing 72 jet,222 atomizer with a metal mesh filter, 17x40 gears tune stock clutch with thick springs and go 48 to near 50 mph with great takeoff at 14 to 14.5° timing with stock magneto,

These people with the high rpm pipes, hpi ignitions all the stuff don’t mean nothing unless you’re on a race track,

I used Moped’s for every day use for 43 years because my vans and cars MPG‘s suck balls,

As long as the streets are dry and it’s above freezing (it could be below freezing but as long as the streets are dry)

The Atlanta boys and Dos cycles are the greatest places to buy stuff for every day use and are great for NOS stuff you name it,

I wouldn’t mind living in that area but my weather blows their weather away as far as rain p/wet roads is concerned, my precipitation, I’m three times the average is lower than the rest of my state so for 43 years I was able to use a moped or small displacement motorcycle instead of a car or bus many times throughout the year,

Re: 70cc e50 not revving out?

Wesley Ambrosini /

> Kyle Washburn Wrote:

> -------------------------------------------------------

> I've dumped close to $250-300 into diagnosing this issue

not to be a dick, but how did you spend that much on trying to rev higher?

Re: 70cc e50 not revving out?

Wesley Ambrosini /

doesn't that pipe die at like 8k?

your gearing puts you at like 8k in the high 30s

so maybe get a higher revving pipe?

Re: 70cc e50 not revving out?

> Wesley Ambrosini Wrote:

> -------------------------------------------------------

> doesn't that pipe die at like 8k?

>

> your gearing puts you at like 8k in the high 30s

>

> so maybe get a higher revving pipe?

Or change the front sprocket to a 14?

Re: 70cc e50 not revving out?

@wes I put a lot of time & money into the rebuild, so I am pissed it's not running like a proper 2 stroke. I'm pretty close to trying to sell it and just get a Zuma or something, it's been quite the trial and error.

@overpriced, I still have my bing 15, so there's potential I could try that again. Although I like the mikuni because it seems to be more reliable with my idle + starting it. As for the top end, I'm pretty close to just buying the airsal kit. My goal with this moped is to have a great daily driver, that is reliable and hits the Powerband/top speed like a two stroke should. Wish you were in Boston I'd pay you to come take a look at this. I've tried almost everything

Re: 70cc e50 not revving out?

Pushrod Fifty /

My stock Suzuki 250 has 2 Mikuni VM20's that use 70 mains. You must be running super rich.

Re: 70cc e50 not revving out?

That's interesting, I might try to order some lower jets then.

I still think the spacing/deck height is messing with my full performance potential. My roommate bolted his airsal on and tuned it and it's golden. I've been trying a lot of different things with my treats kit, but running out of ideas.

I'm going to check the timing, and try to get some lower jets to try. Anyone else ever have a similar issue?

And I've heard this pipe maxes at 8k rpm, but my roommate has the same pipe and the Powerband is ridiculous & the top speed was faster at 14x45 than mine at 17x45

Re: 70cc e50 not revving out?

get the piston crown to barely clear exhaust port, smaller front sprocket, retard timing a little and bigger main, ( havn't messed with vm, but cant u drop the needle to lean out idle)

Re: 70cc e50 not revving out?

Terbo Speghetti /

> John Maxson Wrote:

> -------------------------------------------------------

> My stock Suzuki 250 has 2 Mikuni VM20's that use 70 mains. You must be

> running super rich.

What kinda 250 is that? I think you're lean or it's a four stroke

Re: 70cc e50 not revving out?

I hate huge carbs, I never run bigger than a 15 and my peds rip (and don't suck gas) because they are properly tuned. But since you already have the VM20, some observations:

If you had to go way lower on your main , you would see a black plug. If you don't , then look elswhere.

i am not fond of that piston port kit with a big carb. They can be finicky and getting the port timing right is problematic. I really do think you will have better luck with a different kit, or keep trying different base spacing. It is not burning all the fuel. I would bet your pipe is showing signs of this (wet inside) if you stand the ped up on it's rear wheel blackened fuel will drip out

Re: 70cc e50 not revving out?

For sure you need to upjet, 117 is far too low. Most people don’t actually know how to tune a carb and mikuni carbs are perfect for those people as they will run ok way out of tune. Less than 2 sizes on the main will make the difference between tuned and not tuned at wot. Also double check your Compression and set your points gap to .45mm.

Re: 70cc e50 not revving out?

I'll try to upjetting and see how that works, but I think I'm leaning towards a new kit. It's expensive and I wish I could get this running, but eventually I want to have a solid ped!

I really don't think carbs are super difficult to tune, the bing 15 was a combination of main jet and c clip setting. It wasn't great when trying to start, which left me stranded once or twice (wet plug) so I bought the mikuni.

There's definitely something with the fuel not all being burnt. I just don't know if it's lack of compression, lack of air, or improper tuning but with everything I've tried, I haven't been able to break 37.

Has anyone else run into this issue with a treats kit?

Re: 70cc e50 not revving out?

After that $250 you could of just bought a reed kit.

Okay Check timing

Check squish

Chek compression

Is this some kind of rival? Did you maybe ask your friend for help? If your looking for our help to smoke your buddy and trying to keep it a secret, I would Ask your friend for help instead.

Does he have a ma account lol

Update: you live in Massachusetts? Great! (edited)

Re: 70cc e50 not revving out?

> Kyle Washburn Wrote:

> -------------------------------------------------------

> Hey guys, a few weeks ago I had made a thread about not hitting top

> speed - I convinced myself things were running right until I rode my

> roommates freshly built e50 and almost popped a wheelie the powerband

> hit so hard. Here are the setups:

>

> Me:

>

> - Treats 70cc piston port kit

>

> - Touring head for treats kit

>

> - Mikuni vm20 with 117.5 main jet

>

> - Timing at 17 btdc

>

> - Cylinder spaced with 2 thick black base gaskets and one thin green (3

> total)

>

> - proma circuit pipe

>

> - 17x45

>

> - Temps under 370

>

> Him:

>

> - Airsal 65cc kit

>

> - touring head for airsal kits

>

> - Mikuni vm20 with 125 main jet

>

> - proma circuit pipe

>

> - 14x45

>

> On a straight, I was full throttle at 37-38 while he cruised by me at

> 40+ with much different gearing. Basically, I'm still having the same

> issue where I don't rev out/hit the powerband. My top speed at 75%

> thottle is the same as WOT. My powerband barely hits. I have read that

> squish isn't perfect out of the box on this kit, so I just added some

> base gaskets and now the piston goes slightly under the exhaust port at

> BDC. Before today, I had the same setup except for 1 thick base gasket

> rather than 3, and the hi hi comp o-ring head. It seemed to have muchhhh

> better lowend, but the top end was the same (not revving out).

>

> I've bought a new carb (had a bing clone 15 before) bought a new head,

> moved my needle clip, and messed with the main jet. I've read that

> kitted vm20's are running 130-170 main jets, and 117.5 is the lowest I

> currently have. Regardless, I should be hitting some form of powerband.

>

> Any ideas?

Did you snowboard in USASA competitions back in the day? Kyle Washburn sounds familiar

Re: 70cc e50 not revving out?

Yup I definitely know you lol

Small fucking world!

Re: 70cc e50 not revving out?

Re: 70cc e50 not revving out?

Pushrod Fifty /

Terbo- it's a 2 stroke twin cyl twin carb VM20's 1966 Suzuki T10. Im comparing same carb to a stock setup for a VM20, 70 main and 125cc jug vs his 115 main and 70cc jug.

Dont know if Mikuni changed their jet configurations an numbering since then. Could be. (edited)

Re: 70cc e50 not revving out?

Haha well I'm sure I know you then! Definitely a small world. Those were the good ol' days.

Anyways, the other guy is my roommate. We bought 2 maxis for a steal and decided we were gonna rebuild them fully. Everything is the same except for our top end kit. I'm not trying to beat him, but I am trying to get my bike to run like his and hit the hard Powerband like a 2 stroke should!!

My bike seems to run rich overall, through all ranges. It ran better with my 1 base gasket (.5mm black one), one head gasket, and the hi hi comp head. Low-end was great, but it topped out at 37 and didn't rev out. My new setup is 2 thick base gaskets (.5mm each) and one thin (3 total) paired with a head gasket and the touring head.

I've read on treats reviews of this kit that one guy had the best luck with .5mm of base gasket, no head gasket, and a hi comp head. The Piston apparently is 1mm above the exhaust port, but he said that's how he got the most power. Anyone else try this?

Re: 70cc e50 not revving out?

Im running a 170 main and a 17.5 idle jet on my wifes E50, Treats 70cc with a Vm20, Estoril pipe and 13x45 gears....that thing gets up and goes, Its a swinger 1 and it didnt come with a speedo, but im going to add one and see where shes at. Id say high 30's and thats not wide open.

Re: 70cc e50 not revving out?

> Will I am Wrote:

> -------------------------------------------------------

> Im running a 170 main and a 17.5 idle jet on my wifes E50, Treats 70cc

> with a Vm20, Estoril pipe and 13x45 gears....that thing gets up and

> goes, Its a swinger 1 and it didnt come with a speedo, but im going to

> add one and see where shes at. Id say high 30's and thats not wide open.

So we basically have the same setup - did you do anything to the treats kit before installation? Or are you running the included base gasket, and a head gasket? What head?

My engine seems to run extremely rich, so I'm gonna check timing again, but I feel like my base spacing is messed up.

Re: 70cc e50 not revving out?

> Kyle Washburn Wrote:

> -------------------------------------------------------

> > Will I am Wrote:

>

> > -------------------------------------------------------

>

> > Im running a 170 main and a 17.5 idle jet on my wifes E50, Treats 70cc

>

> > with a Vm20, Estoril pipe and 13x45 gears....that thing gets up and

>

> > goes, Its a swinger 1 and it didnt come with a speedo, but im going to

>

> > add one and see where shes at. Id say high 30's and thats not wide

> open.

>

> So we basically have the same setup - did you do anything to the treats

> kit before installation? Or are you running the included base gasket,

> and a head gasket? What head?

>

> My engine seems to run extremely rich, so I'm gonna check timing again,

> but I feel like my base spacing is messed up.

Its the treats kit for the peeps, I ran the gaskets included, everything bolted right on, no problem at all.

Screenshot_20200130-090435_Chrome.jpg

Re: 70cc e50 not revving out?

If I read right you are at a 117 so we are running a bit different..lol im also in Colorado and that may affect yours compared to mine jetting wise.

I changed my idle jet from the stock 22.5 and im running a 13 tooth gear. Just a bit different than what you got going. Play with you jetting, buy a 10 pack of a range and mess around. The VM20 is so easy to change them out...i love it

Re: 70cc e50 not revving out?

That's the exact kit I bought. I bought a new head because I thought the one in that kit (o-ring head) didn't have the right squish, but I could be wrong. Maybe I'll throw the old hi hi comp head back on.

So you're running the single base gasket, the hi comp head with head gasket, and then vm20 with 170 jet? I also love that you can change the jets so easily on the vm20, which was a major reason I bought it.

Might have to take the cylinder off again and remove some gaskets, and then up my main jet. It seems like itll be way too rich but who knows!

Just curious, what needle clip setting are you on? I'm on the leanest, as the richer settings made it hard to start me engine and it ran extremely rich

Re: 70cc e50 not revving out?

I left the needle alone, it was running well without adjusting it. I try to mess with one piece at a time when it comes to carbs and tuning them. And yes an single gasket, you dont need the Oring with that head. Do a plug chop and see what color you're working with.

Re: 70cc e50 not revving out?

Why do you keep insisting that you are running rich when it sounds like you are experiencing lean bog and need to upjet?

UPJET THAT SUMBITCH!

Re: 70cc e50 not revving out?

Your friend runs a 14 front sprocket, you run a 17 front sprocket. Maybe try to tackle the obvious first.

Re: 70cc e50 not revving out?

Lean bog, from my experience, feels like a surging almost, as if it's got enough fuel and then it doesn't. Rich bog, from my experience, is when it sounds like the engine is almost being choke, and when I give it full throttle while around 50-75%, it runs worse than if I very slowly ease up.

For the head, you sure I don't need the oring? I feel like it will have an air leak. I'm also going to put the smaller sprocket in, but from my experience, a properly running 2 stroke with a pipe and decently tuned carb would still hit some sort of powerband. Maybe I'm wrong? I don't feel like different gearing will magically bring out the powerband, but hey, worth a try.

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