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-   -   Need some 2-smoke street bike ideas... (http://pnwmoto.com/motorcycles/need-some-2-smoke-street-bike-ideas-5149/)

ZXtasy Feb 17th 2019 03:08 PM

Need some 2-smoke street bike ideas...
 
So 2 years ago I helped an old friend get his family heirloom '74 RD-400A running after sitting for about 35 years. I got it to run pretty good, sorted some fuel leaks and he rode it around almost every week that first summer back. (He is in his 70's, so no whoolies.)

It has been 36 years since I had my '76 RD-400, and I never really did any work on it, so now my friend is having trouble keeping it running. I will get it back in my shop when the snow clears, but I am suspecting the intake system components are leaking from age.

Am wondering from some here who have ridden these older 2 strokes for years if maybe I should look at other things; de-carbon the exhaust baffles, reed valve upgrade/replace, add more banana peels to the MR. Fusion for the Flux capacitor?

Thanks in advance for any help or even un-helpful but funny responses.

307T Feb 17th 2019 05:20 PM

Send a PM to Quicklimegirl. She is an awesome resource concerning two strokes and quite the mechanic as well. She and Kevin (Holy Piston) have, and have had, some of the nicest two strokes in the NW.

Parilla125 Feb 17th 2019 10:48 PM

If there are any air leaks through the old crank seals (added air to mixture) it can make for difficult and erratic running. As with any old bike there are too many age related things that can be wrong, which makes it hard to troubleshoot without, well, troubleshooting. Best of luck!

mgfchapin Feb 18th 2019 09:06 AM

Quote:

Originally Posted by Parilla125 (Post 53628)
If there are any air leaks through the old crank seals (added air to mixture) it can make for difficult and erratic running.

This is my first guess. My '93 NSR was getting harder and harder to start until it finally wouldn't. Pulled the crank and its seals were almost entirely disintegrated. Can't imagine a bike almost 20 years older would have any good seals left.

ZXtasy Feb 18th 2019 10:35 AM

Yeah, aged seals get us all in the end...I forgot to add this only has 900 miles on it, but that is still good info as lack of use is worse than wear in some cases.

Thanks, will contact QLG

Flyboymedic Feb 18th 2019 01:08 PM

Paging @holypiston to the white courtesy phone....

holypiston Feb 25th 2019 11:20 PM

What are the symptoms of the ole RD200? Does it still run?


Dirty carbs can be a hassle!!!. Just ask me of the RZ350 w/ JELLY ALL over the carb s...in the weirdest carb passage known to man...I'm slow...took me a whole year to figure that craziness out. disassemble and a soak ina berryman's carb bucket followed by compressed air worked wonders. New jets and all that. Needle jets can get a buch of crap in them along w/ the low speed pilot jets.

Replace everything that is rubber like as was mentioned! Preferable O.E.M.. I hope those are still available w/ the old 200 c.c. bikes. I don't have much experience w/ the RD200, but I have replaced the whole harness (found a used one junkyard judy had for a spare! just swapped it /w the other...too many electrical issues w/ the old harness) and voltage regulator on the RD125. the rectifier can also fail along w/ ignition rotors...which are easy to test on a resistance setting on any garden variety ace hardware multi-meter. Ohy yeah, and ignition coil / ignition switch / bar switch failures I have experienced. I have a nice small "Central Tools dial indicator" that I use to time various RD's. Most are too big to fit under the tank. maybe "economy cycle" online still sells the central tools dial indicators.


Personally, if the ole' man has money :), rebuild the whole motor. Peace of mind! Crank, top end, head work for premium street gas 92 octane...say 135psi and a squish of .036" maybe .040" to be safe....most RD400 heads were generous squish of .070" or higher, but ran hotter w/ a large clearance like that. I think I had a squish of .085"!!! on the Daytona special when it was stock. <---like Frank's hot sauce, I rode that shi* everywhere (after the head mods and mild porting....1st year was the best (higher compression lower squish for premium pump gas)...I had the heads modified for regular pump gas and lower? compression later 125 psi and it SUCKED. yech!! Miss it, but not the rebuilds and stupid blowups on my part. <---paying yer dues...bah-rother!


looks like 2 stroke world went down. I think they have a facebook page, but I don't go on facebook. There's a local guy around where we live that does two stroke rebuilds. I think RB Designs (google) is slowing down, but you never know...he did all my engine work (heads/cranks/carbs/electronic ignition mods, etc).


NOTE: What people can miss when assembling a top end: heat cycles! 1. torque to specified torque 2. ride easy until full warm. 3. kill motor, park, put fan in front of motor, let cool completely. RE-check head torque w/ torque wrench. 4. go back to #1 and repeat until ALL bolts hold a torque reading. My guess is most people run into problems when the heads are only torqued one time w/o rechecking when fully cold....air leak! With new head and base gaskets on the ole RD, I torqued between 2X and 5X. I used yamabond on the RZ350 intake gasket. Must have put too much on...retorqued 9X! until all head bolts held...it was a non oem gasket. but I haven't had a leak yet, probably because of that old school knowledge about heat cycles...important on a/c - l/c two strokes!!

We should have an RD200 manual...so if you need specific pages. don't hesitate. I think I could scan and post pics for you if necessary. I think photobucket might be back online? w/o the payola thing.


I like the U.K. version of Hylomar Blue (Rolls Royce sealant...*raising nose in the air*) on both sides of intake gasket, then hang for 5 minutes and torque.. Like a non hardening urethane? seal...easy removal when disassembling and a lovely royal blue color...yeah. Yambits should sell it or Hylomar M. I don't trust the Permatex version. Yambits (U.K. not U.S.!!!) usually ships fast too. bunch of RD parts of various models offered there.

ZXtasy Feb 26th 2019 08:59 AM

You sir are an embarrassment of riches. When the icebergs flow past my driveway and I can get him to bring it over I will start a thorough autopsy, though it is not dead it runs but does not like to stay running now (last fall) he says. I am sure we will be in touch or follow up on your sources this spring. Thanks!

mgfchapin Feb 26th 2019 09:00 AM

Quote:

Originally Posted by holypiston (Post 53839)
NOTE: What people can miss when assembling a top end: heat cycles! 1. torque to specified torque 2. ride easy until full warm. 3. kill motor, park, put fan in front of motor, let cool completely. RE-check head torque w/ torque wrench. 4. go back to #1 and repeat until ALL bolts hold a torque reading. My guess is most people run into problems when the heads are only torqued one time w/o rechecking when fully cold....air leak! With new head and base gaskets on the ole RD, I torqued between 2X and 5X. I used yamabond on the RZ350 intake gasket. Must have put too much on...retorqued 9X! until all head bolts held...it was a non oem gasket. but I haven't had a leak yet, probably because of that old school knowledge about heat cycles...important on a/c - l/c two strokes!!

Currently rebuilding my NSR250 and didn't know about this. Thank you!

307T Feb 26th 2019 04:18 PM

Quote:

Originally Posted by ZXtasy (Post 53842)
You sir are an embarrassment of riches.

Told ya so. Kevin and Judy are absolutely two stroke wizards.

Parilla125 Feb 27th 2019 05:52 AM

The water cooled need the heat cycles as well.
KX Guru/OEM Cycle and JT Engine in Oregon do a lot of two cycle work, including lapping cases, squish mods and such.

holypiston Mar 2nd 2019 09:29 PM

Quote:

Originally Posted by 307T (Post 53846)
Told ya so. Kevin and Judy are absolutely two stroke wizards.

Actually I had the most mistakes made of any 2T owner. How's a combination 4 corner seizure AND a HOLE in a piston strike you...hated it :o I had a backwards understanding of timing. things like that...just small details :p

owning these bikes over the years...is what I call paying your dues. I've paid a quite a few w/ the a/c bikes..

I just remember a thing here and there. A dedicated 2 stroke site would be much more helpful.

307T Mar 2nd 2019 10:32 PM

You are too modest. You and Judy have and have had some of the nicest looking smokers around these parts. As for the occasional errors, we all had those at one time or another and that experience just increased your learning. I really miss my Bultacos, not that I would want them back again but I learned a lot about riding and wrenching with them. You guys keep the dream alive for the rest of us. Ahhh, I can smell the Bardhal now...:rolleyes:

Sentinel Mar 3rd 2019 09:28 AM

god, i remember kick-starting my rd400f.

buurrrrp. buuurrrrp buuurrrp.
buurrrrbraaaaaaapbraaaaaapppp
brap brap brap
braaaaaaaaaapppp.....

riiiinnnnggggggg ding ding ding ding
rrrriiiiiinnnnggggggg ding ding ding ding

good.damn.times.

note: if you don't grok those words/sounds, you're really missing out.

those who know. know.

Parilla125 Mar 3rd 2019 01:30 PM

One of my fondest MC memories was not that many years ago and I was not riding! Pulled up next to a much modified tricked out Kawi triple with expansion chambers and stingers at a red light. Really nice looking bike. He was turning left and I don't think he even noticed me staring as I was slightly behind him. He locked up the front and did a burn out before he made his turn. It was awesome. Simply awesome. Brought back memories of my H2. I would say it gave me 'wood' but that is probably not 'politically correct'. "I was overly stimulated and gave in to a physical manifestation of my excitement".
Much better...


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