Looking to get into 2 strokes

Yes I can rebuild the Honda tincan cranks. You pretty much need to disassemble the crank to inspect for wear. Not a big deal if you have the equipment to take it apart and put it back together. The shield is actually pretty fragile and if stressed at all it can fracture at high rpm taking out the cases and/or cylinder.

I have taken cranks apart with 1500 miles that probably could have gone another 300, but at the same time I have taken cranks apart at 800 miles that I am surprised they made it that far. If you are going to let the bike sit for an extended period of time I would recommend fogging it.

There are several factors in crank failures. Lack of oil, out of true, excessive rpm on decel, etc....
One of these motors should never be run with a leaner oil ratio that 24:1 IMO.
No matter how true the crank is, improper installation can easily throw it out of true.

Even though a VHM rod kit is similar in price (around $500) to a new OEM HRC crank, the VHM is a higher quality piece. JMO

 

Whats the best way to install to avoid out of true? I don't believe I have the crank tool even though I will need one. I have a friend that I am hoping I can borrow it from...

 

Oh, what is the best "beginner rider" ratio and what do you suggest in terms of baseline jetting starting point and needle position? I have notes from the previous owner, but think he was a full on racer and probably had it set to optimal settings which may be leaner than we'd run... We are in Ohio so, for sea level reference...

 

Heat...I use a piece of steel I made but an old socket will work that has the same diameter as the inner crank bearing. I then heat the piece up to over 500 degrees and set it on the inner bearing race for about a minute. Once the inner race hit 180 degrees, the crank will drop right in.
Now apply your sealant to the left side case and while that is setting up reheat your metal and set on the L/S bearing. Now drop the L/S case on...Once the cases bolts are tightened down, take a plastic mallet and TAP the crank ends till you hear it go tink, tink, tunk...The crank is now stress free in the bearings and should spin freely.

Here is a pretty nice proactive chart for beginners. It does tend to be a little on the rich side, but it will get you close. I have jetted 2 or 3 sizes leaner than "mr. Siezure" to be where I wanted to be.

http://www.fatbaq.com/mainpage.phtml?topic=main_jet_calc


As far as oil, 24:1 beginner or expert.

JMO

 

I used that chart this weekend, and I was wondering if it was reliable. Better on the rich side than the lean side, I guess. Too bad, though. I went 1 higher than Competitive, which probably means I was several jets too high. Not that critical, though, since there were only a couple other 125s and they were much more experienced riders. We were just looking to do reasonably well in our first AFM race on a track we'd never seen.

 

you guys realize you can actually measure the chain to determine its wear. no need to guess and no need to speculate on when it needs to be replaced. measure it. when its stretched beyond the manf. spec, replace it. done.

in my experience, on a 250 (520 non o-ring)...it easily goes > 1year...doing 8+ wknds. for refernce, i get about 2-3 wknds from a top end, following the 500km interval.

for reeds, they are NOT cheap (at least not for me), so i dont replace them unless necessary. you can always see them going south before they fail if you look at them. again, no reason to speculate. you can get them to last longer by: a) not over-revvin your shite; b) cleaning all the rocks off the lips of the cage. alot of little bits get embedded in there and tear them up. i've never had a reed lose tension (which is also easily checked) prior to fraying at its ends.

vince

 

most jetting charts (including the fatbaq one) leave alot to be desired imo. use them w/ a pinch of salt.

vince

 

yamaha's are definitely easier to deal with. the exhaust port architecture is MUCH lower maintenance than a honda. the flip side is that it has a slightly lower output potential. and, you can buy all yam parts at any yam dealer. honda you need to go through one of the grey market guys and hope they dont cutoff the supply from HRC.

there are more honda 125's out and about than yamahas. (yes, there are several yam 125's in socal). but, honestly, there are so few 2T's period, that the argument has less bearing imo now than it once did. get what you like. i'm a yam guy and wouldnt be caught dead on a honda. lol.

next to a manual, first thing to get imo is an eye loupe.

oh, and jetting is simple. and rarely requires the fettling that is portrayed. i hardly ever touch jetting once at the track. and, now that i really only go to one track, hardly every touch it at all!

temp and humidity have a very small effect compared to pressure (i.e. elevation). so if the latter doesnt change much, neither will your carb settings. put it on a dyno and see just how little it affects things, and how wide the operating range can be.

and finally, find a source for AvGas and laugh at everyone else's fuel bill as you fly by them. lol

i'm in HB, have been in/around racing 2T gp bikes for a good while and know enough to be dangerous. i'm not one of the 'experts'...but most of them leave me curious how they got that title. i am happy to tell you what i know. pm me if you wnat to chat.

vince

 

I say don't bother w/ a 2T unless you're racing. If you're gonna do track days, get a Ninja 250 or one of those Aprilia RS125. Or an SV. Or a 600. Or whatever.

I have an Aprilia RS125 for track days. I race the Honda.

Pretty much everything is cheaper than a 125 GP.

With that said, unless you're racing USGPRU (and no bigger than a jockey), there's not much in the way of club racing where you'll be competitive.

I'm 165lbs and 6' tall.

I raced one w/ the MRA... Not competitive, didn't win any races, but managed to get into some pretty heated battles for mid-pack positions. As long as you're realistic and "losing" doesn't bother you - there's a lot of fun to be had on one of these things. I didn't care if I was racing for last place, as long as I had a chance of passing the guy, I was having the time of my life.

Oddly enough my "best" finish was the most boring race ever... Got stuck in 4th behind a bunch of experts on GP bikes and in front of a bunch of odd-ball bikes and Ninja 250s in Colorado Class @ HPR.

Club racing is about having fun for me, period. Of course after racing the GP bike, I want to get my ass on a 600 and smash some motherfuckers... LOL. That's my competitive side talking...

Mine never broke on me, and I beat the fuck out of it. My advice is to read everyone's advice (TDub is the man, btw) and make your own decisions. Working on these bikes is a lot of fun, IMHO. I really enjoyed taking a hard look at mine after every weekend, and I'm not one to wrench, at all. I suck at it, but these bikes have a way of making it really easy and really fun.

Don't be intimidated by the maintenance schedule or working on it. Be intimidated by how much money it's gonna cost. Then revel in the fact that you're on a thoroughbred... There's NOTHING else on earth like a GP bike. Period.

Once you race a GP bike, everything else in life is boring. Try one and you'll see.

 

Great information, like the OP I want to start with something small when I get back. I have done track days on a ZX7,an 01 R6 and a TL1000 and I was tired after two laps, I just did not have the upper body strenght to "flick" a heavy bike. I also hard time with my entry speed, getting those big girls to slow down quickly was not easy despite the race rotors and pads. I am just not keen on all the talk about having to work on them, I am one of those mechhanics that always ends up with a few extra bolts in my hands AFTER I have put the bike back together lol.

 

One thing we agree here for sure.

What was interesting to me is that when I was dyno tuning the bike after changing a lot of parts, is that it made better power jetted rich. Worked for me - more power and lesser chance of a seizure. Little bikes can go.

Sadly not many riders will have a chance to experience what GP was all about before diesels and electronics came about. Even on club level.