New Blaster, new problems.

[thebigrooster]

Ok... so where to start...

First off, this is one of the best forums I've ever been on. Everyone is so nice, answers questions relatively fast, and most people seem to know what they're talking about. Normally I will find a forum for my new toy at the time, and make a post almost immediately because I can't find an answer to my problem. However there is a massive amount of very helpful information here already.

That being said... I think its finally time for me to post.

I got a (according to the PO) 1999 Blaster probably 2-3 weeks ago. When I was at his house, it ran amazing. Pulled hard, throttle seemed pretty responsive through all the gears. I knew nothing about carbs, or 2 strokes... or Blasters, really.

He tells me he mixes 50:1 Amsoil, and that blasters never came with an injection pump (I knew he was lying because of this forum). He also told me everything on the engine has been rebuilt except for the clutch basket, with 5 hours runtime on it. Says the only problems are the rear brake needs adjusted and the exhaust needs a spring.

I take it home, and putt around the yard on the remaining 1/4 tank of his gas, runs great. Picks up the front end through the first 4 gears, has enough power to make me nervous.

Eventually that 1/4 tank of gas runs out. I mixed 40:1 Amsoil Saber oil (I think 50:1 is a little lean on the oil) and it runs like crap. Still starts 1st-2nd kick most times, and will idle ok. Anything above idle though sounds like ass. its like a popping. Lots of smoke on cold startup, but goes away when warm. No powerband, no top end. There is one spot where it will not 2 stroke (i think.) From what I've seen and watched on utube, I think it basically 4 strokes clear through the powerband. I've torn down the carb and cleaned every jet. It has an aftermarket carb with TORS removed. I believe its a 28mm Mikuni. The jets that came with it are as follows:
35 Pilot
220 Main. (It has a FMF Fatty and PC2 silencer, and UNI foam filter. WTF?)
.5 Air jet... i think
182 Q4 -- Needle jet? (still learning.. sorry)
2.5 on another jet I'm not sure of.

And the needle is not stock either. I got the blaster with the needle on the 2nd notch from the top. That's when it ran great.
5F21 Needle.

I bought jets ranging from 230-280 because I wanted options. I have a 260 in now, 2nd notch on needle is better then middle notch with the 260.

The Fatty at the flange and the silencer/pipe connection leaked really badly until today. I tried to seal it with copper rtv, and waiting for that to cure now.

I have checked the plug, its probably fouled but still fires. (Thats next on my list to check, I'm just reluctant to foul another one. Brake clean on the tip maybe?)

I'm also going to clean the filter (I bought the no toil oil kit)

Air lid is on for now.

Any suggestions would be greatly appreciated.

Attached are pictures of the carb... I've been trying to measure the float level and I'm a little confused there too...

 

[thebigrooster]

Sorry about the short novel guys, but I figured that it'd be better to know too much then not enough about my Blasty.

 

[89blaster89]

ill tell you what i would do if it was mine: switch that carb back to the stock 26mm mikuni, you wouldint even be able to tell the difference. stock carbs can be found for cheap. i have no idea how to jet those 28mm but if its anything like a 26mm that main jet is way to small you will blow your engine up. and when you went from 50:1 to 40:1 you leaned it out. 50:1 is richer than 40:1 and dont use no toil oil or filters they restrict air flow ALOT

 

[thebigrooster]

Ive thought about that, however it seems like it would make more sense to keep it since it should work fine when tuning is complete, it costs less since I already have it, and finally, id be paying to downgrade. Not that im against it if thats what i have to do, but it has run very well on that carb before, with a 35pilot and 220 main... O.O

 

[thebigrooster]

One of my biggest concerns is what/where/how do i measure float height on my carb? The pictures i took show roughly 11mm. Im not sure thats right. That carb calls for 22mm height if i remember correct. Pinned all the way against the stopper thing it can hit 22mm, but that doesnt seem to make any sense...

 

[blasterdemon7]

 

[Larry's Shee]

Should be a sticky around here for the carb. Float height is measured from the gasket surface with no gasket. Not from lip where you show. You will need a narrow rule or depth end of calipers to get in there to measure. I would keep that carb, no harder to jet than stocker. Not like you're using a 34mm on a stock engine.
No comment on air filter other than why you changed it. Worst thing to do is changing things when you are having other issues.
As to fuel mix, when you changed ratio you have more oil/less gas = leaner (not good) as it probably was already to lean with 220 main. I know you now have a 260.
Other than normal trouble shooting, start with a NEW plug. Once they get oil fouled hopes of use are greatly diminished. Even though it fires sitting on the head doesn't mean it will fire under pressure/fuel.
Does it have a nice FAT BLUE spark or lazy yellow?
I know there is no TORS on carb, but is the brain box unplugged? I don't recal when the parking brake sensor was added, but make sure yours doesn't have one (03+?).
There is no saying other issues didn't pop up at this time. Start by making sure all electrical connections are clean and tight, add dab of dielectric grease to them. Same with grounds and coil mount. Trim 1/4" off plug wire, reinstall cap with di-E grease.
Search forum for plug chop and/or learn/know how to "read" them.
Might also consider leak down test, at very least inspect carb boot for cracks.

 

[Larry's Shee]

Other than his floats ride on pins in bowl, not pivot from carb body.

 

[blasterdemon7]

The pic was posted to show the points to measure from.

 

[thebigrooster]

The uni air filter came with it, in rather dirty shape. Thats why i got the no toil kit. Should i get a different oiling kit?! Since my floats ride on pins, how do I measure float height? Do I measure from the gasket surface to the brass, then add float height as well?

When I first started reading here, I did unplug the tors box and physically remove it. No difference made, but since I now realize there is no brain box atop the carb, that makes sense.

 

[Larry's Shee]

I'd just use whatever no toil recomends. J W why you just didn't clean old one. Back before they had oil for filters I'd use either ATF or 10-30, squeeze out excess and run it. Sometimes would smoke a little extra if ya didn't squeeze it out enough tho.

 

[thebigrooster]

I still have the uni filter i only bought the oiling kit. I didnt realize you could just oil it with 10-30 or the like. Im going to let the rtv cure for today and clean the air filter, as well as change the plug.

 

[thebigrooster]

As far as adjusting my float height, can anyone tell me where I need to measure from? I wonder if that might be a contributing factor to my problem... Thanks again for all of this help.. it makes all the difference.

 

[Larry's Shee]

Just re-read your post and noticed you had spec for that carb. Presuming it's correct, not just Blaster spec? Measured from inside of gasket flange without gasket to the tab that the floats push up. That's why I mentioned steel rule or depth end of caliper.
Hopefully someone will ID the carb as to model, what it is off of, and if you have correct float measurement.
As to filter, if you have filter oil use it, as it is a "sticky" substance. If not and don't want to get any, use my suggestion, as that's what was used long before they had "filter" oil.

 

[thebigrooster]

The carb is from CPW, it had a CPW sticker on it that has fell off since I've cleaned it. According to Carburetor Parts Warehouse its a VM28, which I'm sure is right.

http://carbparts.com/mikuni/vm20_44.gif
^^That blowup diagram matches mine exactly.

I got that 22mm float height spec from this forum, in this thread.
http://www.blasterforum.com/carburetor-138/float-heights-how-adjust-them-50565/

 

[thebigrooster]

Got a ruler... of sorts, and if 22mm is right... its maxed out on that float arm. It has a stopper my index finger is on and when that's bottomed out, the tip of the float arm is at 22mm. This doesn't make any sense to me.

 

[Larry's Shee]

OK I think I found it. It will depend on exact model of carb you have.
It starts at lower right corner of page 151 and continues to top left of 152.

Sure hope this helps : http://www.drivehq.com/file/df.aspx?isGallery=true&shareID=7134489&fileID=522925104

 

[Awk08]

Got a ruler... of sorts, and if 22mm is right... its maxed out on that float arm. It has a stopper my index finger is on and when that's bottomed out, the tip of the float arm is at 22mm. This doesn't make any sense to me.

you want to turn the carb and hold it on a slight angle to measure the float height, like shown here......

it should just barely be touching the inner needle, not depressing it,
holding it pefrectly horizontal like your pic shows may allow the needle to be depressed giving false measurements.

the mikuni float heights i listed in this thread are from the CPW website...........
http://www.blasterforum.com/carburetor-138/float-heights-how-adjust-them-50565/

yet the link larry provided calls for a different setting ???....

—Fig. S12-3) should be 15MM (0.59
inch) on TS 250 R, J and K (VM 28 SH)
models and 9.IMM (0.358 in.) on TM
250 (VM 32 SC) models. Level on all
models is adjusted by bending tang (B​

—Fig. S12.2).

 

[Braaaptor]

I have a Sudco manual for Mikuni carbs at the house. That is a VM 28 carb. I bet the float height spec is in the manual. Ill check when I get home and post the results.

On your running problem, a lot of it may be due to the Saber oil. It is designed to be mixed 100:1. While I definately would NOT mix that lean in a Blaster engine, you can encounter running/bogging problems if you mix an oil intended to be mixed 100:1 at a richer ratio, such as 40:1. Just FYI. Id go with an oil designed to be mixed at 32:1 or 50:1. Some people may disagree, but I have run my Blaster on AMSOIL Dominator mixed 50:1 for two years with no problems.

 

[Awk08]

Just FYI. Id go with an oil designed to be mixed at 32:1 or 50:1. Some people may disagree, but I have run my Blaster on AMSOIL Dominator mixed 50:1 for two years with no problems.

to further confirm what braaaptor says......
i've run the amsoil dominator at 32:1 and my bike ran like chit