MB100 development

[bucketracer]

A better view of the filter modified to be a header tank by adding a breather.

[bucketracer]

Because a few people have asked about the GP engine, to save wading through 270 pages, these links go to the more relevent posts about the 27hp engine. Different link collections can be found on the decade pages 80-90-100.....260 etc.

Attachment 238154 27rwhp 1978 Suzuki GP125

A direct line to a bunch of Team ESE engine development posts ..........

[F5 Dave]

. .
As Dave has for some reason got his back up. . . . .

Have I? I was just saying that I wouldn't overbore a 100 too far, I wasn't throwing any sort of hissy fit, - the 80?, who knows?

[husaberg]

I've fitted various ignitions over the years and they have all seemed to be good. I've now got an Ignitech. Funny thing is that I can now alter the timing to anything the bike wants and it seems that apart from one little point way up in the powerband a flat timing curve is what it wants. Fixed timing would seem to be OK, as tested on the dyno on my motor.

Interesting I always were lead to believe the retarding at high revs a little increased the over rev potential a little. When You say way up is that where it is?

[speedpro]

13,000rpm(ish).

That might change with the new carb when the power jet is turned off.

[koba]

Bike is running a Mikuni carb that's been machined out to 27mm and what looks like a home made exhaust system with a can of unknown origin.

Just a thought I had on this - What is the carb off? Has it run well with this carb before?

It sounds from your first post that you are having trouble jetting it lean enough not to bog but rich enough to not cook.
Could that be If the Air fuel correction doesn't match the current motor because it's off a 4-stroke or something? (making it too rich at some points and too lean at others)
(Unfortunately I'm only coming up with more questions rather than the answers I'm sure you want!)

What do you base the "too lean" on AF ratio meter on the dyno?

(EDIT: I can kind of see that on your pic but my eyes aren't the best..)

[koba]

Now I worked out the zoom I can see that pic better.

Was that thingy speedpro pointed out blanked off or still open?

If it was open it would be interesting to see how another dyno session goes with it blocked off.

[Hilleye]

It's currently still open. I think it's just the oil injection inlet. You reckon that could flow enough air to make a difference?

[Yow Ling]

I'm not 100% familiar with those carbs but I think the little white plastic fitting next to the fuel inlet hose needs to be blanked off. Without that you will have a hard time tuning it. Otherwise it looks OK(ish). Make the effort to get a good pipe on it and if you want get a port rubbing and send it to me. I'll run the software over it and see where it's at. If it's old-school you may be better off dropping the cylinder and reporting.
Looks like a reasonable sort of bucket to get going on.

I think the white plastic fitting that Speedpro refers to needs to be left alone , it has feelings too!
Here is a pic of a standart TZR250 carb with a little hozey thing attached, it goes into a gallery which turns right just behind the blanking screw at the bottom of the bellmouth, at the bottom of this gallery is a small jet , I guess its an air jet as there is no airscrew on the carb I have.

Maybe of interest is the brass nipple beside the fuel in hole what is its job, is it hidden in hilleyes picture?

This is the same type of carb as Hilleye has.

[husaberg]

I think the white plastic fitting that Speedpro refers to needs to be left alone , it has feelings too!
Here is a pic of a standart TZR250 carb with a little hozey thing attached, it goes into a gallery which turns right just behind the blanking screw at the bottom of the bellmouth, at the bottom of this gallery is a small jet , I guess its an air jet as there is no airscrew on the carb I have.

Maybe of interest is the brass nipple beside the fuel in hole what is its job, is it hidden in hilleyes picture?

This is the same type of carb as Hilleye has.

I am with Yow on the Plastic vent. It is the same as my one. It was always left open to the catch can on my bike I have looked for my carb notes and it says I always ran between a 210 and a 230 main in mine .But mine was a higher state of tune I guess.

My carb which was a bit trick in the very early 90's Well that's what I told myself.It bloody cost $75 then which was about 2 days apprentice wages at the time.
It was always ran with a foam filter (Uni) and came without a throttle cable and a choke the STD MB100 Keihin choke fitted just fine and the only cable I could find to suit then was a DT200 one.
I read somewhere in PB the max they can be bored was 29.2mm or similar I imagine that would be a real mission. I have some info on these carbs on the computer somewhere it came from a tzr250 tuning story if I can find the site I will post it if it has any relevance.

The great thing with these carbs is they suit the angle of the cylinder with the RD reed rubber and are short and have a huge fuel fitting as well.

[speedpro]

It's not oil injection and I'd be surprised if it was left open or had a jet in the line. Why would you put a jet in a line rather than direct in the carb. It would have been a controlled air bleed to the emulsion tube. I'd lay money on it needing to be blocked off.

[husaberg]

It's not oil injection and I'd be surprised if it was left open or had a jet in the line. Why would you put a jet in a line rather than direct in the carb. It would have been a controlled air bleed to the emulsion tube. I'd lay money on it needing to be blocked off.

I don't rememember Yow or anyone saying it had a jet in the vent?

Here is the f3 carb mods I would not say all his mods are Nesercary but here is the Naughty boy page I couldn't get the page to work on the net but I was able to piece this together with a page I had saved.

But as I said above my was never blocked off on my bike that had the same type of motor and the same carb. The power jet was never blocked off either.

[koba]

You reckon that could flow enough air to make a difference?

A tiny leak can cause havoc with correct carberretion. Yes, very much so.

[koba]

I'm not experienced in dyno tuning but from that graph you posted, the meagre power output and tuning problems you seem to be having I'd suspect there is something wrong somewhere. The carb would be the first logical suspect.

[F5 Dave]

I'm with Mike, block that puppy.

There is an jet to the emulsion tube & the pilot system at the front of the bellmouth. Why have another air passage?

Answer, probably open a solenoid to lean it off when at idle to pass an emissions test on Jap models. My RGV 32mm carb has the same doofer & there seem to be several versions of RGV carbs even between the usual VJ21 & 22 models presumably for different markets. I couldn't get it to run better with it open or even with a tiny jet in it as I attempted to use this for tuning to see what it liked best.