Posts
2217
Joined
8/16/2006
Location
Bend, OR, USA
Edited Date/Time
11/22/2013 1:11pm
Hi Guys,
I just picked up an 05 YZ125 for Junior last night, it has a badly dented pipe and I want to get an aftermarket expansion chamber. Not sure which one to get FMF SST or a Fatty. I looked into having Pacific Crest fix the stocker which I most likely will but we can have a new one quicker to ride this weekend. Also, if anyone has a line on a set of SSS front forks let me know. I think I have to change the entire clamp system to convert.
I just picked up an 05 YZ125 for Junior last night, it has a badly dented pipe and I want to get an aftermarket expansion chamber. Not sure which one to get FMF SST or a Fatty. I looked into having Pacific Crest fix the stocker which I most likely will but we can have a new one quicker to ride this weekend. Also, if anyone has a line on a set of SSS front forks let me know. I think I have to change the entire clamp system to convert.
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Definitely get the stock pipe fixed and keep it as a spare. It's a good pipe. Seemed broader than the Fatty where the Fatty seems more punchy like it tightens up the powerband.
There is tons of info on these bikes (and the 250) in the Yamaha 2-stroke forum on Thumpertalk. Lots of guys don't like the SST because they say it causes burnt pistons. They say it gives you a false plug reading of being rich so guys keep jetting leaner and leaner to compensate until they fry their engine. Don't know, never tried it.
I tried the V-Force 3. It does make the bike more snappy or responsive but it leaked like hell and sucked air. The bike would develop a lean bog when it got hot and things expanded. If you run one, make sure you seal it up well with Moto-Seal or some other gas-proof sealant.
First thing you need to do is pull of the clutch cover. Look behind the clutch basket at the shift-stopper. Determine if it has the original 2005 part with the ball bearing or if it has been replaced with the 2007+ part with the solid roller wheel. The bearing on the 2005-2006 one frequently falls apart and the ball bearings go through the entire tranny. Get the 07 part in there. It only costs a few bucks and is easy to replace.
It must be unleaded because it's sold from the pump and can be put in street bikes and cars. Not sure on the ethanol content. The pump will usually have that sticker that says "may contain up to 10% ethanol" but it's unclear if that is just there as a leftover from when some other type of gas was in that pump or whatever.
Anyway, it runs good in my 2-strokes. Nice and crisp, no detonation, and no spooge.
On my CRF450, after putting in the 13.5 piston and stage-2 cam I was getting some pinging under heavy load. Started using the 100 pump gas and cleared it right up.
Read this thread I started for our 06 YZ 125, helpfull info... Enjoy your new bike!
YZ 125 Tips and Tricks
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The YZ125 is known to have a prob with rusty head bearings and it seems to be related to the seal above the top bearing allowing water past. The common fix is to run the seal from the 250F. My bearings got notchy so I replaced them and got the 250F seal. It appeared to be the same as the aftermarket seal that came with my Pivot Works bearing kit and did sit down in the groove better than the stock seal, ever so slightly. No probs since.
How much does your kid weigh? Stock 250F springs are probably stiffer than 125 springs.
125 rate is .42kg and the 250f is .44kg or .45kg depending on the year.
I did buy the shift detent part as well, just got all the parts tonight. A good buddy of mine warned me of the problems with the bearing falling into the transmission and demo-ing the entire deal(his did while running the Idaho City ISDE) It trashed his entire tranny. The seller actually let me drain the oil into a glass container to check the oil to make sure there were no metal chunks in there. It was perfect. My boy is 16 years old and just shy of 170lbs. He's heavy for it but really likes riding two stroke 125 over the RMZ250 he had. I am cool with it as long as he is having fun. He said he likes the challenge of having to actually carry momentum through corners
Thanks again for all the input guys
I get my race gas at the Shell at Houghton/Valencia. I used to get it at the Quik Mart at Houghton/Irvington.
According to this http://www.racegas.com/fuelfinder You can get Sunoco race gas at Tucson Raceway Park across the road from MCMP. Never tried it.
Pit Row
IMO, 100LL avgas is a better 2-stroke fuel option. It jets close to pump gas and provides good throttle response and contains no ethanol. I run it in all my 2-strokes.
You can get it at the Bend Muni airport for $4.99/gal. The airport is unattended after 6 and has self serve pumps after hours. If you want to try it, I'd suggest that you go after hours so you don't have to talk to any airport personnel. It's legal to use 100LL in a dirt bike, but some airport guys don't know that.
thanks for the info!
edit: NVM! Would get it on the way to the track!
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