10000000th tuning thread

Looking for some tuning suggestions. If anyone has a similar setup, chime in and let me know what jets you're running.

Bike is a tomos step through with an A35

Setup is:

A35 airsal kit, case matched

Malossi 4 petal Reed block

Phbg 19 on a matching MLM intake

Tomos 4 pole stator full advance w/ parmakit CDI box

Technigas next pipe

Treats custom cut 44mm o-ring touring head. (This is the one with slightly less compression for every day riding)

30x24 gearing if that matters to anyone

I'm not sure what my actual compression is. Im going to check tomorrow when I get a chance to ride it up to AutoZone before they close.

Current jets are 90 main 43 idle and needle at richest position

It's still getting hotter than I'd like at WOT. It was getting up to almost 420* with an 84 main jet (thank god I didn't seize it). I also didn't have my timing at full advance yet when it was reaching these temps.

I just went to a 90 and now it's topping out closer to 370. Still too hot for my liking considering my cylinder is made of aluminum. My setup before was never getting above 300 but I've changed a lot of things since then.

I've got a bit of a bog at 2/3 throttle but I'll probably get that worked out playing with the needle once I've found my main jet.

Temps are definitely dropping immediately while I'm at idle. So I'm pretty sure I'm good there.

So who's got an idea of where to go from here.

It's 4 stroking a little at WOT so I'm going to try an 88 main next and see where that gets me.

Re: 10000000th tuning thread

So I should say that I've read all the wiki stuff on tuning a phbg and have done it before.

The title is probably a bit misleading as I know what I need to get it tuned. It's less a question about what to do to get it tuned and more about how hot the bike can get without me being worried about it. It's been hovering around 340-350 for the most part while out riding now and that still just seems hot to me for an aluminum cylinder.

Maybe I'm just worrying too much.

Re: 10000000th tuning thread

So what's your question or your problem? Sounds like you know exactly what your doing....

Re: 10000000th tuning thread

> Buddy Shirey Wrote:

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

>

> Current jets are 90 main 43 idle and needle at richest position

>

..........

> I just went to a 90 and now it's topping out closer to 370. Still too

> hot for my liking considering my cylinder is made of aluminum. My setup

> before was never getting above 300 but I've changed a lot of things

> since then.

>

> I've got a bit of a bog at 2/3 throttle but I'll probably get that

> worked out playing with the needle once I've found my main jet.

>

> Temps are definitely dropping immediately while I'm at idle. So I'm

> pretty sure I'm good there.

>

> So who's got an idea of where to go from here.

>

> It's 4 stroking a little at WOT so I'm going to try an 88 main next and

> see where that gets me.

My $0.02, if I was running with that data I’d drop the needle back to center position and upjet a hair rather than down jetting.

Everybody always says 85-90 jet for PHBGs on mildly built 70s but at sea level that’s always left me on the lean side.

Re: 10000000th tuning thread

while u at autozone, borrow their lazer temp gauge if they have one to double check yours.

Re: 10000000th tuning thread

> pat splat Wrote:

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

> while u at autozone, borrow their lazer temp gauge if they have one to

> double check yours.

Yea I've been wondering if my gauge is off. So I may do that. Some of the insulation around the sensor is worn. I wasn't sure if that would affect readings or not.

And Tommy buzzard, I guess my real question is, is 360* hotter than it should be with this setup, and should I be concerned?

Like I said, before I broke it down and changed stuff it was rare if it ever got above 300* but that was with a different kit, a 2 coil stator and stock CDI box.

I'm not riding it more than a mile or two at a time for now because I'm paranoid about breaking stuff. The bike has been out of commission for a little over a year and I just got it back on the road 3 days ago. I'm not really wanting to have to rebuild it again anytime soon if I can help it.

Re: 10000000th tuning thread

> Thomas TPRF Wrote:

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

> > Buddy Shirey Wrote:

>

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

>

> >

>

> > Current jets are 90 main 43 idle and needle at richest position

>

> >

>

> ..........

>

> > I just went to a 90 and now it's topping out closer to 370. Still too

>

> > hot for my liking considering my cylinder is made of aluminum. My

> setup

>

> > before was never getting above 300 but I've changed a lot of things

>

> > since then.

>

> >

>

> > I've got a bit of a bog at 2/3 throttle but I'll probably get that

>

> > worked out playing with the needle once I've found my main jet.

>

> >

>

> > Temps are definitely dropping immediately while I'm at idle. So I'm

>

> > pretty sure I'm good there.

>

> >

>

> > So who's got an idea of where to go from here.

>

> >

>

> > It's 4 stroking a little at WOT so I'm going to try an 88 main next

> and

>

> > see where that gets me.

>

> My $0.02, if I was running with that data I’d drop the needle back to

> center position and upjet a hair rather than down jetting.

>

> Everybody always says 85-90 jet for PHBGs on mildly built 70s but at sea

> level that’s always left me on the lean side.

I'll probably try that this afternoon once I get off work. Its definitely 4ting at 2/3-3/4 throttle. It 4ts a little at WOT but its not immediate. Usually happens after I've been on a straightaway wide open for a few minutes. It's hard to tell if it's the needle position or main jet causing it.

Re: 10000000th tuning thread

400 max temp sounds good for that setup

those a35 airsals are pretty bomb proof

do you have an exhaust leak? they'll run hot but not be lean.

Re: 10000000th tuning thread

If your at a constant 360-390 at full throttle holding it for a long time and the temps never get above that then it's fine. A little 4s is good to play on the safe side. I'd adjust the needle like said before and leave it alone

Re: 10000000th tuning thread

I don't believe so. I used one of those crush gaskets when I mounted it and it's also not super loud at the cylinder like it would be if I had an exhaust leak. I'm thinking it's just tuning at this point. Ive ridden a bit today and it seems to be hovering around 350 now and hasn't gotten above 375 since yesterday.

Also I've been reading a bit today and it sounds like more strain on the engine can also cause higher temps. When it was staying as cool as it was before I still had 16" wheels and 27x22 gearing. Now I've got 17" wheels and 30x24 gearing. So I'd say there's definitely more of a load. That may be part of why it seems like it's getting so much hotter.

Sounds like from what people are saying I should be good as long as I'm not breaking 400 anymore which I'm not. It just doesn't sound right to me that an aluminum cylinder would be fine with sustained temps of 350+ but I'm not a scientist. so what do I know?

I just need to keep getting it dialed in and I'm sure it'll be fine once I have my carb tuned all the way. It's already way better than it was yesterday and the old lady is working all night so I've got ample time this evening to tune and rip around downtown Louisville.

Re: 10000000th tuning thread

> Buttcheeks BUZZARD Wrote:

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

> If your at a constant 360-390 at full throttle holding it for a long

> time and the temps never get above that then it's fine. A little 4s is

> good to play on the safe side. I'd adjust the needle like said before

> and leave it alone

Yea that sounds good to me. I'm going to take the needle down another notch before I ride again and see where that gets me. I think I just needed some reassurance more than anything. Ive tuned this bike before and I'll be able to do it again. I've just only been in the moped game for around 3 years now so I still tend to second guess myself sometimes.

I'm just anxious to get it dialed in so I can start working in the 76 Blanco that's been sitting in my shed and start learning something other than tomos.

Re: 10000000th tuning thread

Also, does anyone think I would benefit at all from going to a BR8HS plug instead of the BR7HS I'm running now?

Re: 10000000th tuning thread

> Buddy Shirey Wrote:

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

> Also, does anyone think I would benefit at all from going to a BR8HS

> plug instead of the BR7HS I'm running now?

Yeah 100% maybe even goto a BR9HS this will lower them head temps a lil (edited)

Re: 10000000th tuning thread

I went to a BR8HS and that helped with the heat a little. I've also changed the timing a little and i'm going to play with it some more as I think this is where part of my problem lies.

I definitely need to get my carb tuned right and I'm getting closer. This is always a bit of a process and i know I'll get it. I'm currently at an 88 main jet and it seems like it's doing well at WOT. I think i just need to mess with the needle a bit to get it perfect.

Either way, I've got some questions for anyone who's ran this parmakit CDI box. I hooked it up to a timing light and it is definitely retarding as RPMs increase. I know it's supposed to do that but I now have confirmation that the box is actually working.

I currently have it set just slightly more advanced than the most advanced timing mark on the Tomos cases. When RPM's increase it buries the firing mark past the most retarded timing mark on the case. When I first made this post I had the stator literally as advanced as it would allow me to. Even when it was set there it would move the firing mark past both timing marks on the case.

So how far will this box actually retard timing?

Do I still want it to be firing within the two timing marks on the tomos case while I'm at higher RPMs? It seems like I would but maybe I'm wrong.

I've heard of people using a dremel in order to be able to advance timing even further on a tomos stator when using this CDI box. Is this something I should consider?

I know I don't want it to be firing after it reaches tdc. I'll need to hook up the timing light again and make sure that isn't the case. I'm currently waiting on a new choke for my carb because it came unthreaded while I was riding monday night and I lost it to the road. So I can't ride until I get that part from treats later this week. In the meantime I'm just trying to get a better understanding of this CDI box.

So I'm curious how other people have set up this box when running it on a Tomos. I'm getting closer but this is the first time I've ran a box with a curve. I read in the wiki that some boxes will have an initial advance at idle and then start retarding as RPMs increase. Is the parmakit one of these boxes?

If anyone has any info on the curve of this box it would be greatly appreciated.

Links to other threads related to said box would also be good.

Sorry I can't be more specific with the timing. I need to buy a new micrometer and until then I won't be able to know exactly how many mm btdc it's firing.

Re: 10000000th tuning thread

spencerrrrr r /

Re: 10000000th tuning thread

Thank you, that is exactly the information I was looking for.

Discovered a couple days ago, that a big part of my problem is a leak at my reed block.

I'm going to take it off and replace all the gaskets etc and hope that it fixes the heat problem. I should have known I had a leak when no matter how I would change jetting the problem never went away.

Re: 10000000th tuning thread

So i've gotten my bike tuned and it feels smooth through the whole range of throttle. The problem with overheating was due to a pretty serious air leak at my reed block. i got that fixed, downjetted and now my temps are staying between 270-300. It will occasionally hit 350ish after a long run at WOT or uphill.

So not necessarily a problem but i'd like to see if anyone has any suggestions on what I could do to make my setup hit 9k. I'm currently topping out at about 8700 rpms, which puts me at ~48 mph for top speed. I've heard that this technigas next pipe revs to about 8500. So i'm wondering if that's what's stopping it where it is.

If that's the case then is there a way to use the timing to squeeze out another 300 rpms. According to the wiki, when you retard ignition timing you raise the temperature of the gasses as they exit the exhaust port. This makes them move faster and in turn raises where the powerband is.

So if I'm understanding this right, if I was to retard my timing a bit more then that would raise the rpm where my pipe hits.

So I guess my question is can I hit 9k with this pipe and setup by retarding my timing a little bit more, or am I stuck hitting a wall at 8700 rpms until I get a higher rpm pipe?

Re: 10000000th tuning thread

OG Crazy Wayne /

You can raise the exhaust port a half a millimeter with the top of it flat for 12 or 14 mm with radius in the corners of the top and or shorten your header 1/2 inch.

My friends who race go karts and have put them on the dyno have found that Peak power happens on air-cooled cylinders at 418 degrees Fahrenheit with the reading taken at the base of the spark plug with a thermal coupler.

Re: 10000000th tuning thread

> OG Crazy Wrote:

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

> You can raise the exhaust port a half a millimeter with the top of it

> flat for 12 or 14 mm with radius in the corners of the top and or

> shorten your header 1/2 inch.

>

> My friends who race go karts and have put them on the dyno have found

> that Peak power happens on air-cooled cylinders at 418 degrees

> Fahrenheit with the reading taken at the base of the spark plug with a

> thermal coupler.

I've been considering raising the exhaust port just a bit but hadn't gotten around to it yet. I'd shorten the header but don't have the resources to weld it back together. I may be able to find someone locally to help with that.

As far as what you said about the peak power being at 418*, that seems like I'd seize pretty fast if I was getting that hot all the time with my aluminum cylinder.

Re: 10000000th tuning thread

OG Crazy Wayne /
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