Messages

I do have straight die grinder, a Dremel etc, but no right angle handpiece. And since those are pretty expensive, I am looking at having this done by a somewhat local shop. I can easily deal with intake and exhaust ports myself, but do not intend to change timing, maybe just improve the exhaust port finish to slow down carbon buildup.

Gents,
I have a spare set of stock RD 350 cylinders, still at stock bore, that I am considering having bored to +.25 or +.50 mm, as well as converting them to RD400 head gaskets and fitting dowels to locate heads.
Is it worthwhile having a local 2 stroke shop clean up the transfer ports first. Just removing any steps and casting flaws in the upper part of the transfer ducts and the ports. And maybe cutting the boost ports a bit deeper as well. No plans for more exhaust port duration, however.

Just have to share this vid I just came across:
https://youtu.be/YwA7bco9mVw?si=GmQ4GIFpXoN_zfKh

Not directly relevant as such, but:
Did the 73 RD perform better in period tests than the 74/75?
"Restricted" air flow and #120 MJ vs more open air filter and #140 MJ.
Also, my A model (74), although sold as a 75 in Norway, as no B models were imported, had a #105 MJ installed when I first worked on it. Apparently installed by the dealer at a service way back in the 70s. Possibly supposed to be a retrofit of baffled filter and #120 MJ, but somehow smaller jets were installed.

I also had a broken kickstand bracket on my RD350. I ended up making a reinforcement bracket, that tied to both the bottom AND top plate of the frame crossmember. It is now rock solid 😀

This is possibly way too political, but as a Norwegian, i.e European, it is mindblowing to watch current events unfold......

Looks really nice! I have a few questions though:

How is the length compared to a stock RD350 or RD400 swing arm?
How does the weight compare to a stock swing arm?
Is the RD350/400 wheel axle long enough?
Is the shock mount in the same position as stock, measured from swing arm pivot?

Did you kick it with fully open throttle when getting the 90 psi reading? And is there a long hose on your compression gauge?

(When you consider the effective volume above the exhaust port is maybe 125 cc, and combustion chamber volume is maybe 22 cc on an RD400, the added volume from a hose will reduce pressure reading significantly)

That will be a pretty extreme street ride 😀

I mean they look good. but performance is a whole other ball of wax. I really hope they work out.

If judging by the length in the pics, they do not seem to be built for a high rpm peak. Which may be a good or a bad thing, depending on expectations.

AFAIK, the only 34 mm Yamaha forks with the calipers behind the sliders are 1976 XS650C and pre-Daytona RD400.
The XS sliders are a bit longer than RD sliders, and also have larger OD.
The RD400 sliders are also different from the 350 ones,in the top end/ seal area. So best replaced as a pair.

Here is some inspiration if you are still going the OEM route.  100 3/8" holes per rotor and they were also thinned down to around 5mm.

Thanks for sharing, looks great. I've now made up mind to go the blue dot way....the challenge is obtaining the specs for the flange and adaptor for the RD350B (1975 model) is a challenge as mine has the OEM fork legs with the caliper in the front unlike the RD400.....

You can swap the fork legs left to right, if you don't use the oem speedo.

thanks. I forgot how easy a piston port is to jet for pipes w no other mods, and of course fucked it up last night    went up too much on the main  and it just wasn't good. so basically I need to get maybe 1 larger than stock and try it. they do sound good. also, w some fanagaling I can retain the center stand. I did have to sing the pipe in at the sidestand bolt,  and will have to relocate the rear pegs. but, I like em.

Lovely looking pipes. And bike!
I wish JL would make RD pipes more in that style. Their "classics" do not look half as good IMHO. That low, straight 70's style appeal more to me than more kicked up designs.

All that being said half a pound is half a pound.

On a lightweight bike like an RD, less unsprung weight is REALLY noticeable on bumpy roads. A more extreme example is when I converted my XS650D from the oem twin 267 mm discs (more like boat anchors, really) to a single 320 mm ISR disc, and a Brembo 4 pot caliper. Combined with an alloy front fender, Ti fasteners and alloy bearing spacers, I lost around 5 kg/ 12 lbs of unsprung weight. From around 16 kg to around 11 kg IIRC. The difference was noticeable before you got into second gear.....

Hi All: Is there any alternate gear shift lever that is a direct fit on the RD350 gear shift shaft? Has anyone tried the YZ125 shift lever? The shaft size seems to be same as of the RD based on the oil seal dis.

Long story short, the belly of my exhaust pipes are huge and not tucked under the frame. The OEM lever tends to hit the side of the belly interfering with down shifting....

Most all Yamaha levers, including XT250&500, XS650 will fit. And some Honda as well