New Member RD400C

[Blue]

Hello all, as title suggests I'm new here.

Recently sold an RS250 and upgraded (sure you'll agree) to a lovely RD400C, I believe built by Stankflapper, and a fine job he did.

Bike sat for about some months in a showroom until the previous owner gave in to me the poor bloke. Fuel very stale and carbies had to come off for a serious clean. I've also had to add some turn signals that came up neat and subtle. Also reset timing points checked oil pump etc.

Made 45hp which I'm stoked with happy days.

Went for my first decent ride on the weekend chasing a blue slip and it's pretty flawless and not as uncomfortable as I had anticipated. Very surprised at the performance goes pretty hard.

After about an hour I went home and listened to the bike and heard a pretty feral sound coming from the left cylinder area. My RS250s were all pretty noisy but new to RDs I was hoping someone could take a listen [link below] and confirm that this is not good. I feel the bike has been run in sufficiently but still didn't wring its neck.

Some pictures also attached I had to shrink them right down.



Thanks for reading comments please!!!!

Blue


https://www.youtube.com/watch?v=UCkdH29V0n4

[BRG1200]

Ah, piston slap ;-)
Welcome! Nice looking bike, did you change the seat?

[EPApolice]

If it has LC pistons fitted then it will rattle. Just take the heads off and look to see if you have a clearance issue if you are worried about it, the AC head gaskets are reuseable and there are only four bolts holding each head on.

[Blue]

Nah I didn't do the seat, it was bought pretty much as is.

I'll take the head off on the weekend and have a look. As far as I know it's not using LC pistons.

Appreciate the replies guys wish me luck.

[BRG1200]

look forward
to seeing you around on here

[Blue]

Pulled the head off the noisy cylinder today. Images attached. The marks on the intake side can be felt with my fingers. Link below to Youtube video showing me moving the piston back and forth with my fingers.

While I was tinkering I pulled the oil lines off at the carbs and alas, no oil came out nor could I see any in the lines.

Haven't tested the pump yet so not sure if it's buggered, needs adjusting or has blocked lines. Lines look new.

http://www.youtube.com/watch?v=uSaTiGrGyw4&sns=em

Any comments and/or advice?

Thanks

Blue

[Blue]

Did only two photos come out? Try again

[Blue]

One more

[hybrid]

The piston looks oily.. I don't think it's lack of oil.

But just by sight... that looks like a lot of piston clearance in those bores.

You can put a bit of premix in the tank, start the bike, remove the oil lines (block the hole in the manifold) and pull the pump to full. You should see oil start dripping out.

[EPApolice]

They look like Mitaka pistons to me and they are for the LC. Not a big deal but you will get a rattle even with a new bore but everyone runs them without incident and that looks like new pistons in an old bore. Do what Hybrid said to check the pump but I suggest a complete engine strip because looking at that you cant thrust that engine and the AC motor is cheap to rebuild.

[hybrid]

What makes the LC pistons rattle in the AC bores?

[EPApolice]

Something to do with the clearance and there is a tang on the bottom that needs to be removed. You can leave it on but some motors have eaten themselves when it broke off. Even when the bore is done to suit the piston they still rattle. I have them in a few bikes with the tang removed and have high mileage on the motors without an issue

[hybrid]

Ahh Ok, that tang is an RZ thing. You should remove it on the LC too.

[Blue]

Thanks again guys. Can I push the friendship and ask where you'd recommend buying parts from? Any to stay away from?

Perhaps recommend a good engineer to bore my cyls?

EPA you mention a complete strip, you mean splitting the crank case, as well?

[hybrid]

Any machine shop should be able to do the bores for you if you give them the pistons and clearances required.

What you need to be careful of though is chamfering the ports again afterwards. A bike shop or karting shop should be able to look after that for you if you can't do it yourself.