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#1

Turning Wrenches / idle screw does not raise the ...

Last post by older2smokers - Today at 02:00:23 PM

I put a PWK on a 95 Yamaha wr250z (replaced the orig Mikuni).  bike will start and run okay (depending on exact needle and jets) for about 10 minutes.  idle speed then drops way down and at that point the idle speed screw does not change the rpm.  the air screw (AS) will affect how quickly it returns to idle but doesn't change the idle speed.  bike will die if AS all the way closed or if out 4-5 turns.  slide is open a good 1/8" compared to my KDX the slide is barely open.

I've checked the jet block gasket (which was new), the float level, and the jetting/needle is at or close to the 95 yz sizes (they came stock w/pwk). also the carb is a Power Jet model but that is blocked off.  I also have a clone carb (ChiHin i call it) that does this same this.

I'm waiting for a new cable to re-install the Mikuni until I can get some insight on this issue.
thanks for any and all input.   

#2

Turning Wrenches / Re: Rebuilding vintage 2 strok...

Last post by RDnuTZ - Today at 10:55:01 AM

What bike(s) are you talking about here? When you say "rebuild"- are you just talking about the top end of engine? There's always a max limit on bore size at some point. I have lots of vintage 2 stroke single cylinder Yamahas, so an example of that is Yamaha typically only offered 4 bore oversized pistons from stock, but Wiseco typically offered up to 8 oversizes. The problem is going to be availability of pistons you can find. The biggest oversizes are usually rare. LA sleeve used to offer a new installed sleeve with a matching stock bore piston kit. Don't know if that is still true or not. Some plating companies would also plate back to stock factory specs and offer a piston kit with it.

Can't really be much more help unless you tell what bike you have here. Good Luck.

#3

eBay/FB Marketplace/Craigslist watch / Re: 1979 Yamaha RD400 Daytona,...

Last post by Yamanatic - Today at 10:49:53 AM

Seems like there was quite an interest, with all the different bidders.
Wondering why this went for that much.
Time to get mine out
M

That's the nature of the auction - the actual worth does not matter near so much as having at least 2 bidders that want it bad enough... 

#4

Turning Wrenches / Re: Rebuilding vintage 2 strok...

Last post by Oliver - Today at 10:40:53 AM

more details on your bike would help define things, but in many cases you can resleeve old vintage cylinders once you are out of bores. Check LA Sleeve and Wiseco for starters to see what they have. Some of the older bikes already had chrome bores and starting in the 1980s or so specialized coatings like Nikasil were introduced that could rebuild the thickness of your cylinder liner to stock and go from there. Just generalized thoughts here.

Thanks. If you go the sleeve route is there any real limit to how many time you can rebuild the original engine? I mean, could someone get five or more rebuilds?

#5

Turning Wrenches / Re: Rebuilding vintage 2 strok...

Last post by RDnuTZ - Today at 10:20:59 AM

more details on your bike would help define things, but in many cases you can resleeve old vintage cylinders once you are out of bores. Check LA Sleeve and Wiseco for starters to see what they have. Some of the older bikes already had chrome bores and starting in the 1980s or so specialized coatings like Nikasil were introduced that could rebuild the thickness of your cylinder liner to stock and go from there. Just generalized thoughts here.

#6

Turning Wrenches / Rebuilding vintage 2 strokes

Last post by Oliver - Today at 08:37:21 AM

Hi! I'm new to two-stroke engines, so some of these questions might seem pretty basic to you guys. Is it possible to fit a vintage two-stroke with a replaceable cylinder liner if parts are not easy to come by for that engine? If so, would there be any real limit to the number of rebuilds that I could get out of a vintage cylinder? Thank you.

#7

Haus of Projects / Re: RD350 forever project

Last post by Perattzi - Today at 12:48:59 AM

Thanks for the compliments! I just cut the caliper bracket on a band saw and used a, drill press, belt sander and file. That said I want to make a nicer one. Currently it is 3/8" aluminum plate, but may redo it with 1/2". I made the rotor spacer years ago in a machining class. Wish I had access to a mill to now to finesse the bracket. Floating caliper noises take some getting used to! Only issue I'm having with the brake is the bleeder valve is weeping ever so slightly. Hoping it's just corrosion at the sealing seat and a new one will solve it. Other issue with  a real brake is that it has exposed how bad my forks are! My to do list is:
-brake bleeder
-fork springs/oil/possibly emulators
-polish front hub and lace an rim to match rear, the chromed steel just looks off
-new tires, sadly the Avons are old enough to be in high school 😆
-sort turn signals. They light up but do not flash, despite wiring in a claimed LED relay
-sort out leaking carbs and once that's solved dial in jetting better
-redo seat foam under the upholstery. The person I hired do it used way too soft of foam.
-replace leaking clutch rod seal
-look into hydraulic clutch conversion
-possibly fit a Bultaco Metralla style bikini fairing, with some sort of LED lighting. I'm kinda tired of the round headlight look.

Gonna need some guidance with this stuff! 

#8

Haus of Projects / Re: RD350 forever project

Last post by SoCal250 - May 07, 2024, 11:25:37 PM

Great looking bike! Well done sir!
Love the harness work and other details (front brake, pipes, etc.).

#9

General Chatter / Re: Mark Atkinson Speed of che...

Last post by SoCal250 - May 07, 2024, 11:21:18 PM

No! I hope this isn't true.

#10

eBay/FB Marketplace/Craigslist watch / Re: R5 in the MD for $650

Last post by dgorms - May 07, 2024, 10:41:49 PM

East coaster tempting us West coasters!