Big one or standard??

[Benman]

Simple question. Am I better off derestricting my factory exhaust or using a big one expansion pipe??? I am currently using the big one silencer.
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Ben1972

[69chris]

if your standard exhaust is still in good nick id be tempted to use that
iv got an aftermarket front pipe in my garage (big one i think) and the only plus i can see is that its a fair bit lighter than stock,
oh, and its held on by springs so you dont have to keep distubing the bolts/gasket if you wanna take it off............ so thats 2 pluses

but it does also blow a bit from the slip in join so thats a negative.....

fucked if i know

[dangerousdave]

stick with your standard pipe if you can mate, build quality is much better than the Big One pipes.

I blew a huge hole in my standard pipe where it exits the cylinder, so bought a Big One front pipe. I never got it to run right with the Big One pipe on it. In the end I got the standard pipe repaired properly & stuck that back on and it was much better.
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1988 Kawasaki KMX 200

Previous: Yamaha YZF1000, ZZR600, KMX200, DT50, KX80, CG125, PF50

[Benman]

Ok gonna stick with the standard. Will I still need to rejet once I deristrict it???
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Ben1972

[dangerousdave]

a few of the other 125s had a collar in the header pipe of the exhaust which had to be knocked out - not sure if this if the case with the mtx125.

once that was done then the main jet needed to go up by a couple of sizes.

im sure somebody one here will be familiar with the bike and will be able to give you the info you need.
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1988 Kawasaki KMX 200

Previous: Yamaha YZF1000, ZZR600, KMX200, DT50, KX80, CG125, PF50

[Benman]

Yeah that's the case with this one. I picked up a couple of jets. Standard is 112 so got a 120 and a 122.5.
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Ben1972

[Benman]

So I took the standard pipe off today to have a look at taking the collar/restrictor out and can't see how I am going to manage to do it. Any ideas??? So have put the big one pipe on for now until I can figure out how to sort it. Love the sound and really seems to fit well with no blowing. Got 120 and 122.5 jets. Standard is 112 so what should I try first??
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Ben1972

[Benman]

Wow put the big one on today with a new gasket and new springs. Again wow what a difference!!! Sounds mean and goes like shit off a shovel. Straight through all the gears no stuttering and no bogging at all. Haven't changed the jet yet. Can't see a need at the minute. It's like a different beast!!!!
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Ben1972

[Joenitro]

Keep an eye on the plug to make sure that it isn't running lean. They do run great just before they self destruct when they're lean

[69chris]

nice one, but just to be safe keep an eye on the plug over the next few miles to make sure all's well

[69chris]

must type faster

[Benman]

Was running rich before I swapped it so hopefully that's sorted the difference out. How will the plug look if too lean???
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Ben1972

[Benman]

Do ya think I should swap the 112 jet for the 120 just to be on the safe side. Ya gots me a bit worried now.
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Ben1972

[69chris]

if it was running rich before then just do a plug chop and see what colour you have with the current jetting,
id be suprised if you get away with just putting a full performance system on and not have to re-jet tho tbh

just remember - jets are cheaper than pistons

[Joenitro]

You should be worried mate. It almost certainly will be lean with that pipe. I would put a bigger jet in there but I'm sure there are far better qualified people on here that could give you more help

[Benman]

Ok got a 120 and a 122.5. Standard is 112 so which do you think???
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Ben1972

[69chris]

iv got a 125 in bits that had one of those exhaust fitted, i'll go find the carb and see what that was running

[Benman]

Thanks bro!!!
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Ben1972

[69chris]

errrr, not sure this'll help - its a 112

the needle is still on the 2nd groove from the top as standard, all thats different is the pilot air screw is 1-1/5 turns out where its 1-3/4 as standard - would that be really noticable ??????

just had a look in the manual and the 200 only uses a 118 mainjet in a 26mm carb so ?????

sorry bud, its over to someone else but all i can say is it was running sweet and didnt sieze up or do anything nasty in about 5000 miles of constant thrashing

[Benman]

Yeah the 112 is the standard and don't think the pilot makes any odds really. What should the plug colour be if its good?? Tia dry but blackish at the minute.
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Ben1972

[69chris]

have a gander here.......

https://modernvespa.com/forum/wiki-2-stroke-carburetor-set-up-technique

its a bit 'vespa' but the idea is the same

[Benman]

Good call that's tomorrow's project sorted. Definitely need to look at idle mixture as the revs race up when starting so that's where I will start. Will let ya know when I get there. Thanks for the heads up bud!!!!
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Ben1972