New Blaster, New to 2 Strokes. Very Turned Around.

[MrShark]

I picked up a 2005 Blaster that supposedly has a 240cc BBK, there is no markings where the stock cylinder has the 195cc so I am unsure what's actually in it. Guy included the stock cylinder, but there is no second head. Checked jet while doing TORS delete and it has stock 230 mail still, middle clip position on needle. Running 91 no ethanol fuel at 40:1 with Lucas Semi-Syn Oil. Elevation ~570ft.

Also has:
FMF Powercore 2 Silencer / Stock Pipe
Oil injection delete
TORS Delete
Filter lid "channel" removed so it opens full on the box

Air filter was disgusting so I replaced with a Maxima ProFilter. Also checked the plug at that time and it was pitch black and wet, I can't wrap my head around more CC's on stock main being rich.
Installed new plug and got the idle as high as I could with the air screw (2.5 out) and just got back in from a 15mile play session that had some full throttle blasts and constant throttle cruising. Full throttle, full blast I only got 43MPH on my tracker with 20" rears. Felt like a dog off the line and never really felt full power. Got home and pulled the plug and again it was black, but not wet.

Looking for some guidance from the 2 stroke gurus, totally lost. Should I toss in a 320-340 like a lot of 240 guys are using and see what happens?

 

[82cutty]

Welcome to the forum...First you'll need to remove the head to measure the bore to see if you actually have a big bore sleeve in there . 72mm . I wouldn't run it anymore to you find this out . Then do a leakdown test to make sure it doesn't leak anywhere . Then we can help you with jetting . Your main is too small either way . Get rid of the stock pipe . If its a stock bore up the main to 250-260 with the mods you have . And do your pre-mix at 32-1 .

 

[Larry's Shee]

If it were me I wouldn't pull the head. If it ain't broke don't fix it !!
Unless you really have to know if it's a BBK.

I'll bet a buck it's a chitty Chinese cyl !! Don't know that other cyl away , you may need it !!
There is a good You Tube vid by O'Connor Racing that shows how to identify the different BB cylinders, minor differences on the outside. Don't know if he mentioned if the crap cylinders have any tell tale markings on the outside when he did his evaluation of them ( not on vid, search Niche cylinder on here)

Not sure on your lid description/modification.
I would start with a good carb cleaning, set the float, make sure brass washer is under main jet. The number of turns out on the air screw could indicate something a little bit wonky.

IMHO should only need one size up on main for air filter, as that seems to be only power adding mod, silencer don't count.
Read up on how to do a plug chop.

WELCOME !!​

 

[MrShark]

If I were to pop the head off to double check the bore, is the gasket reusable or will I need a replacement on hand? I do know that the washer is under the jet.

 

[Larry's Shee]

IIRC O'Connor has a vid on how to anneal the copper head gasket. Never tried it myself (yet) You do need a torque wrench to tighten. Best to loosen nuts opposite of tighten sequence and in stages I.E. do each 1/4 turn. Jmho.

 

[MrShark]

Found a major source of my headache, there was a missing bolt on the intake. Got replacement bolt, then raised needle to 4th down clip and reset air screw, found highest idle at 1.5 so good start. Got out for a ride, rips hard but could tell its way lean on the top. Max mph 43 full throttle, 46mph with throttle stop at 3/4 so I plan to buy a bunch of jets and start playing. Should I drop the needle back down after upping the main?

 

[82cutty]

I would put the needle on the middle clip . With your air filter...lid off and running pre-mix a 230 main isn't good . Throw a 260 in and plug chop .

 

[jbuckster07]

agreed, 90% of the time, the middle clip is where you need to be with a stock carb.

 

[MrShark]

Tried a 260, kind of boggy, went to 2nd down clip, seems to pull hard. Still need a chance to plug chop and see where I'm at.

 

[jbuckster07]

I would suggest stop messing with the needle clip, toss it in the middle spot an leave it there. I cant even think of a thread on here where people have changed the needle clip from the middle (besides using a non stock carb) The main jets are what you need to be changing.

Did you ever find out if its a BBK? If it is 260 is WAAAAAAY low. FMF requires 260 on a stock bore if memory serves me right. If its a BBK I would say you need to be up in the 290's+

 

[MrShark]

I haven't pulled the head yet to check. I tried a 300 to start and it was a dog. I have 260,280,300,320,340 to play with. I watched the BBK identifying video and my cylinder doesn't match any of them, unless they bored a stock one and milled off the stock casting idenfiers for some reason. I might not be the best to tune either, due to me not having experience with a manual quad. Should I be able to fully engage clutch after I get rolling and open throttle or will even a properly tuned engine bog. I drive a manual car but it's not 100% relateable.

 

[nick20555]

If its bogging when you pull in the clutch and hit the throttle then your jetting is way off. We can't really tell you much about your main jet unless you figure out the needle first. I would put it in the middle position and set your throttle stop screw so that you can only give it half throttle and then ride it around and see how it feels. If you don't know about the throttle stop screw then what I did was take one of the 3 screws on the top of the throttle box and put it in the threaded hole on the back of the throttle box (the side that faces the front of quad). You can turn it in the limit your throttle. Just move your throttle a couple times to see its full range and then turn the screw in until it stops the throttle at about half its full range and ride it around. This will tell you if the needle needs adjusted. Once you have your needle right then we can move onto your main jet.

 

[MrShark]

I didn't mean to say it bogs when just reving. I mean once I get rolling in 1st and then pin the throttle it was bogging and then clear up and take off. That was when I had it on middle clip position. Once I moved it to second from top it seemed to accelerate a lot easier from a dig.

 

[82cutty]

I didn't mean to say it bogs when just reving. I mean once I get rolling in 1st and then pin the throttle it was bogging and then clear up and take off. That was when I had it on middle clip position. Once I moved it to second from top it seemed to accelerate a lot easier from a dig.

Makes sense...stock needle position is 2nd. clip .

 

[82cutty]

I would suggest stop messing with the needle clip, toss it in the middle spot an leave it there. I cant even think of a thread on here where people have changed the needle clip from the middle (besides using a non stock carb) The main jets are what you need to be changing.

Did you ever find out if its a BBK? If it is 260 is WAAAAAAY low. FMF requires 260 on a stock bore if memory serves me right. If its a BBK I would say you need to be up in the 290's+

I think we all thought he has an FMF pipe...but he just has the muffler with the stock pipe . That explains why it's running better on the stock needle setting (second slot)

 

[nick20555]

Good point cutty. I would still say he needs to do the whole throttle stop screw method with it on the 2nd position because he mentioned that he is taking off and pinning it. That still isn't the proper way to find if his needle is good. If it rides good at half throttle then he needs to take the throttle stop screw out and do some WOT plug chops.

 

[82cutty]

I did that when I put the PWK on . Worked good for jetting the needle

 

[MrShark]

Thanks for all the guidance. Since the stock pipe seems to be such a choking point I nutted up and ordered the FMF Pipe, figure I already have the jets to get in the ballpark. I believe I also have the Vito reeds, just by looks.

 

[82cutty]

Once you get the FMF put the needle in the middle and a 280-290 main should be close with the lid off and pre-mix. Start with the air screw at 1.5 turns out.

 

[MrShark]

Sorry for the delay, was on vacation. Installed pipe and 280 jet, and set clip to middle slot. Seems laggy in middle so removed lid completely and it woke up. Still need to plug chop but it's pulling the wheels up without me doing anything.