Yamaha R5/RD350 Bastard...finally building again

NoahAbs

New Member
Hi all,

You probably don't remember me, but I had the very beginnings of an RD250 build going on last year. Then I sort of screwed up the frame, life got in the way, my job shipped me halfway across the country, etc. etc. etc. I am back now, and the bug bit me again, so I sold my '05 SV1000 (which was great, and lots of fun when I was in AZ but not so practical for a city driver in NYC.) I bought and with the help of a buddy who is way more knowledgeable about these old Yammie 2 strokes, have put together a bike cobbled from some of the guts each of us had lying around. The engine is frpm a 71 R5, was bought from a guy in canada who had just completely rebuilt it. The rest of the bike (frame and components) is from a 73 RD350, and the tank is from a RD400. I had accumulated a good bit of parts for the RD and kept accumulating afterward, so here is my progress. So far:

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I am planning to make a different seat (it was one my buddy had lying around) and ditch that weird tail light (some odd bit I had in a box.) Still need to figure out the rearsets some, bend the kickstarter, swap out the current clipons for a nicer set I have, maybe a billet top triple, and paint the beast. I am also considering trying to relocate the battery (i am only running head/taillight) and the oil tank (I found a flat one from a mx bike that might work.)

Oh and here's one of me on it, I wasn't trying to look mean, I had only a few seconds to run from my camera to the bike before the auto-shot went off- thats the look of pure determination!

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Thanks for looking, and thanks a bunch to the guys (diesel, rocan, boomshakalaka) who gave me some advice last time around!
 
ill be following this one!

where in nyc are you? i know that neighborhood...

lets meet up sometime and talk bike!
 
Carroll Gardens, Brooklyn my man. Probably could tell its BK from the brownstones. Where are you at?
 
hey! glad to have you back.. I definitely remember your 250 build. Sometimes you gotta throw in the towel, but its just good to see youre at it again with another build, and it looks like a great place to start.
 
Thanks man- was a perfect storm of stuff, project got out of hand, living situation wasn't helping (rocan and the other nyc builders know what i mean) and then i got shipped to arizona for seven months so i ended up selling a bunch of stuff so i didnt have to deal with it. glad to be getting working again although already there are some gremlins. bike was running ok, then died and i had to ditch it in the city. gonna pick it up this weekend and try and figure it out. seems to be idling funny, big flat spot initially under throttle. not totally sure if thats the issue, if its fuel starved or if a wire is shorting the bike. i work on my bike on the street so once night falls im SOL bigtime.
 
I feel for you man... hearing about people working on their bikes in small sheds, crawl spaces, the city streets, etc. makes me appreciate the fact that I have a garage to do my wrenching in.
 
NoahAbs said:
Carroll Gardens, Brooklyn my man. Probably could tell its BK from the brownstones. Where are you at?

park slope! you bastard, your close!


meet up next week? ;D
 
Rocan that's crazy man, I'm just a short shot away from you. The bike right now is sitting in Manhattan, I need to go in with my truck and pick it up tomorrow. It was acting kind of fuel starved and now it doesn't want to kick over. I haven't been able to look at it in the day time so I can't really diagnose what is wrong, fix it, and ride it home, so the truck it is. I will let you know when its back and spinning. Next order of biz is trying to figure out relocating everything under a seat, and of course making the seat. The one that is on it right now is crappy and I don't like how its angled. Thinking about going with something like the WM Club Black seat, a bit squarish like the RD400 tank but low and flat to keep the lines smooth.

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So been trying to sort out some gremlins with the bike running. The idle seemed off, like the bike was idling too low and kept dying, so I turned the idle screws to get it in a range where it seemed like it was consistently sitting in the 1300 or so rpm mark. The bike starts decently easy, seems like fuel is running well, etc. but after a bit of running/riding it dies and then doesn't want to start up. I suspect weak electrics, either at the battery or points. The front headlight seems pretty dim, and I'm not running any signals on the bike so I think it should be brighter. I am going to try tomorrow to run it with a new battery. Any other ideas about what would make it start, run, then die and not want to restart?
 
By sealed well I'm guessing you mean oil gasket seals? The oil system is letting oil out when it shouldn't and making it run too rich? I was going to go wrench today, but its raining now, and since I am a strictly "on-the-street" operation that means no dice. The weak headlight doesn't make you think its an electrical thing? The PO also did a funny wiring job, there are a bunch of loose connectors which i think I'll just wrap in electrical tape and tuck away.
 
sounds like your having some of the same problems with your r5 as i was/am, i think the new battery should help if the lights dim mine was doing that a while ago, the light would be dim then it got to the point that if i turned the light on it would kill the bike but then i charged the battery and it fixed that problem. Also did you have to modify anything to fit the rd400 tank on there i've been wanting to find a bigger tank for my bike.
 
Yup, put in a new battery, and even though its smaller (4.5 vs 5.5 aH) it seemed to run better. Noticed that there seems to be a leak at the headers, so I'm gonna try and silicone seal those tomorrow...that could explain it to.

The tank doesn't fit perfectly, had a bracket made up for it to attach right. I'll take some pics if you want.

Also, some upstanding New York driver knocked the bike over, and was nice enough to stand it back up. Bent the crappy clip ons I have on it right now (which are the POs ghetto fab job) but I have a few sets of nicer ones I was planning on trying on it anyway so its all good.
 
Looks sick! love the 400 tanks shape. The comment about the engine being sealed, means that the case halves themselves, crank seals, top end gaskets, intake manifolds, etc. all must be sealed tight so no air leaks in causing a lean condition. Really the only way to test it is to do a leakdown test. Just google the term 2 stroke leakdown test. If the engine is leaking anywhere, it really will give you hell trying to tune, and may eventually seize. Timing has to be right on the money as well. The two strokes really are a bear to sort out, but when everything is sorted...it's soooo good.
 
Swapped out the bent/crappy/home-fabbed clip ons for a set of TCBros I'd accumulated, way better.

Bike seems to be starting and idling better after I played with the idle screws a bit and with the new battery. That being said, I watched it run for a bit and rode it around the block. Observations:

1. Seems like one cylinder if firing better than the other. Way more pop coming out of the left side pipe, and way more sweet 2 stroke smoke.

2. I fear that the leak theory may be correct. While just watching the engine while I crack the throttle there seems to be smoking coming from somewhere around the engine. It could just be the right side header, it doesn't seem sealed well, I need to get some silicone and seal it up. Still, its worrisome.

I may just bring it in for someone to sync the carbs. With the DG pipes (which are good, crappy? I have no idea) right now the bike is not pulling off the line at all, only waking up around 3 or 4k or so. The more people tell me that 2 stokes really need to be dialed in, the more I am not confident that my C-/D+ skills will get it running right. I think I'd rather have a pro dial the carbs down while I spend time and effort on other parts of the bike that are more design/mechanical and less internal.

Thoughts? Life preservers?
 
You can do it man with some patience. I understand not everybody wants to, or has the time, to spend hours reading about how to make your bike work right...and then spending several more hours trying to make it happen. However, if you do plan on keeping this bike for any amount of time you're gonna have to invest in a few special tools and learn the basics of tuning your 2 stroke. Do you have a manual? I can send you a .pdf if not.

I would just start from point A. Before anything else, do a compression test. If it's below 100 or so, the engine is on its last leg. However, my RD was only like 115 before I tore it down, and the thing straight up scared me at first it was so quick. If youre over say 120, then you should be fine for awhile. A top end usually cost around $325 for pistons and boring. What do the plugs look like?

Stock coils are shit, they will not do the job. Inexpensive ones can be had...my bike is using some for an old VW automobile, big fat spark. Check to see if your pipes are full of oil and carbon...clean them up if so. Next build a simple leakdown tester, and do a leakdown/vaccum test. http://www.2strokeworld.com/forum/index.php?topic=1570.0

Basically, you just remove the exhaust and carbs, plug them up with freeze plugs(google it...you can get them at auto parts stores or plumbing supply places)...get a fitting so you can pressurize the engine to around 5 or 6psi and an air gauge to watch that no pressure is lost. If its leaking you will probably hear the air escaping. The whole mess can be make for less than $30 easy, or spend $200 on motionPros kit.

Then set the timing, are you using points? If you upgrade any one thing on this bike, get an electronic ignition. You can make the points work well enough, but its not the best way. To set the timing right you need to buy a dial indicator to find TDC.

Then take your carbs apart and see what size jets are in there, and what clip position the needle is in. Clean everything if needed. Synching the carbs is pretty easy on a twin, remove the y boot and just watch the slides after you take the slack out of the throttle cable and then just adjust them until they rise at the same time but have the correct amount of free play at the cable.

Are you premix or using the injector?

When I bought mine I was too afraid to mess with anything...now I am confident enough to take one about any issue that may come up. Our engines are dead simple, no cam chains, valves etc. They just need some love. Research research research. The 2 stroke forums are a mecca of info.
 
Thanks guys, sorry I haven't been posting too frequently recently. Got my hands on a 1989 Honda VTR 250 Interceptor. Don't know who remembers the bike, its as far from a bomber black rat bike as possible. Looks like a Barbie accessory, but its a nice honda v-twin in a light package. Got it back up and running and have been ripping it around a bit.

Now its running well and I can turn back to the RD. I will get this sorted out, too far into it now to blink.
 
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