Fresh start, fresh problems

[Jspooner]

Sounds like a rattly piston to me.

[paul1478]

I am by no means an expert but sounds like a piston to me also.
If this is not what it is I need to fix my bike to because it sounds about like that just not quite as loud.
Pipes sound great by the way !

[Striker1423]

So I suppose its possible the bore job was done too loose. But on the same side as when it was the 250? I'm really over this bike if that's the case. Last thing I need is a piston exploding in another piece of equipment I have. 

[SUPERTUNE]

Striker, What pistons did you use?
Do you know what piston to wall clearance it was bored to?

If using Pro-X pistons you have to buff off the coating off the measurement point of skirts to get a proper measurement of the piston,
most shops that have no idea about RD's make this mistake and bore the cylinders too big.
Now you have a rattly topend after breakin when the coating wears off. It can add .0008 to .0012 of added clearance if you don't do this when boring for finish size.
Chuck

[SUPERTUNE]

It will still live for a while even if this happens. Just warm up the engine good before hard wide open running.
Chuck

[Striker1423]

Chuck,

Here's a few pictures I took when I did the swap over. He marked both pistons and jugs with his measurements. They are Wiseco Pistons.
https://imgur.com/gallery/tIKb2CV

[SUPERTUNE]

If you want good results with this bike making power and running good, get rid of the stock airbox, do a primary needle jet conversion on the stock carbs.
This squish chamber is really bad design when stock also.
Go read some old internet articles about modifying the top end for proper modern head chambers designs. 
So sad that a lot of this stuff I posted about this is gone with the old forum... :(
I did a whole thread on John's RD250 to 350 build I did last year....
Chuck

[SUPERTUNE]

Chuck,

Here's a few pictures I took when I did the swap over. He marked both pistons and jugs with his measurements. They are Wiseco Pistons.
https://imgur.com/gallery/tIKb2CV

Bad link...
Wiseco pistons do make noise, so that is not a problem...
If it's quiet, that's a problem!!
C

[SUPERTUNE]

I just finished another RD350 build for Dan Sawyer yesterday and it rips.
I will have to start posting everything I did on here with his RD350.

Send me a PM and we can talk...no need to give up. I can help!
Chuck

[SUPERTUNE]

Chuck,

Here's a few pictures I took when I did the swap over. He marked both pistons and jugs with his measurements. They are Wiseco Pistons.
https://imgur.com/gallery/tIKb2CV

OK, the links works now...I can see your machinist was in a hurry and mis-wrote the sizes on the cylinders.
He wrote 65.01 on cyl. A and 65.02 on cyl. B  That is not correct I'm hoping...
I'm sure he meant to write 64.51 for A and 64.52 for B
At those #'s your right on the $$ for piston clearances @ .0031 in (.078mm)
Just you can't make a mistake with jetting and tuning setup. At this piston to wall you have no wiggle room if your running it on a hard full pace run.
Start rich until you see about 50 miles or more on it to breakin the pistons.
On my jobs I start about the same.
Get timing to 1.8mm to 1.7mm
Use fresh *93 fuel, do not use old fuel. I like 6 weeks or less with tuning RD's (IN A SEALED CAN!)
Ethanol based pump fuels will suck humidity right out of the air and turn to water in your bowls!
Pour some in a coffee cup, let it sit in Florida 15-20 mins and the whole bottom will have water in it!!
Chuck

[SUPERTUNE]

Your main problem is you need to cap the crossover on the manifolds!!
Use the carbs as they were intended to be used with stock bleed needle jets and air box...Stock manifolds did not have a crossover other than some euro RD400's but they have special needle jets in them from Yamaha to compensate for a crossover tube.
If you want to keep the crossover tube (or in my case on my builds I use my TSR/Barlow designed boost bottle) you should go to a Y boot air cleaner and do the primary needle jet conversion (known as the Dave F mod)
I can do all the mods to the carbs with a full rebuild, this can be in the $150-200 range with shipping (Never use any old jetting parts in the carbs, these are over 40 years old and who knows who's poked what at any of the jets and how much wear the needle jets and needles have)
Chuck

[SUPERTUNE]

Well, this is the seemingly last thing that's bugging me on this bike. Not sure what this noise is, but it was making it last year on just the 250 as well. When warm it's got this rattle from the clutch side that gets the loudest when good and hot. Sounds like a bag of marbles. I figure it could be the clutch is just worn out, but I don't quite know. Again for the sake of knowledge the crank is new, etc. Clutch doesn't slip and the noise isn't really heard when at speed. But that is probably just from the wind noise. 

https://www.youtube.com/watch?v=MhU0yL9ymYE

Clutch hubs do wear out the cushions in the hubs and I have replaced a few of them.
Have to grind off the factory rivets to get the hub separated from the gear, tap some threads in the rivets holes and use new rubber bushings and special flat headed screws.
Ebay here for the cushions.
Chuck
https://www.ebay.com/itm/Yamaha-banshee-clutch-basket-cushing-bushing/322387510046?hash=item4b0fcb031e:g:Q2kAAOSwiONYK1j-&frcectupt=true

[Striker1423]

I figured the clutch basket was pretty hooped when it had 6mm of forward and backward play in it.   So, I looked and can get the dampers and a new basket that takes tapered Allen screws on yambits for around 100 bucks. Seems reasonable. Would suck if I did the work and it still made that noise lol. But I'm already so far in the hole here it's a do it or make the bike go away kinda thing at this point.

[SUPERTUNE]

I figured the clutch basket was pretty hooped when it had 6mm of forward and backward play in it.   So, I looked and can get the dampers and a new basket that takes tapered Allen screws on yambits for around 100 bucks. Seems reasonable. Would suck if I did the work and it still made that noise lol. But I'm already so far in the hole here it's a do it or make the bike go away kinda thing at this point.

Yeah I know... I see it everyday, people buy wrong parts and modifying from stock with no knowledge of what they are doing or why.
Internet can be too confusing. I try to be very specific on how to modify RD's to get the results we want.
Believe me, just hit 59 and started doing this RD stuff at 19 with a brand new '79 Daytona, went back to a '77 RD400 and won a AMA 410 production championship in '80.  Talk about skinny...I was very skinny then.

Here's from about 1984 at Rockingham.

[Striker1423]

So, when I turn the bike over with the side cover off when the bike overcomes compression and I spin it over a but more by grabbing the clutch it makes a very slight clank noise. This is just turning it over slowly. Not sure it isn't the gears meshing. So I'll try putting a bit of lube on the gears and record what it sounds like.

The only thing I can think is the bottom end not being happy. I checked the rod when I put the new top end on and it didn't have any up and down play. So perhaps it's the piston making noise  after all. I'll update this tonight when I'm home and can get a better look.