Recent Posts

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The Piston Broke / Re: Changes to Petrol
« Last post by tony2stroke on June 21, 2021, 10:48:59 PM »
Thanks for sharing that.
Thanks so much for the response, sorry to hijack this post as well   :D.  Will something like this suffice or do I need a metal jacketed one? And sorry I'll start a different post.  Thanks again.
Aircooled RD Tech Help 250cc and Above / Re: RD400C slight engine seizure
« Last post by Numbskull on June 21, 2021, 09:43:18 PM »
A blocked air intake will make it rich making it far less likely to seize  :-\

I'm talking about the main jet nozzle hose going up to the front of the airbox. The fitting can get
clogged in the elbow choking off the air to the main jet nozzle. Easy enough to check.

Aircooled RD Tech Help 250cc and Above / Re: Correct jets
« Last post by 5port on June 21, 2021, 09:18:57 PM »
After I cleaned out the carb it ran around the garden ok left it idling for a minute while I got my gear on to go a run on the road
and it was all dead no power before I got to the end of the road took the plugs out, wet. It was running pretty good until I put the new carb kits in. The choke is sealing ok but it will start from cold with no choke. What is the procedure check air jets behind the blanking balls are clear. Thanks

If it starts easy from cold (less than 20*C engine temp, so almost always overnight UK temps!) without "choke" at all, it is probably very rich on the Idle air screw setting or the Pilot jets are too big.  You are getting gen Mikuni so, as well as making sure you get 22.5 Pilot jets, do make sure the Idle air screw adjustment is "One and a Quarter" full turns out from lightly seated.  Cheers

Aircooled RD Tech Help 250cc and Above / Re: regulator & brushes wiring 400c
« Last post by pidjones on June 21, 2021, 09:04:59 PM »
Insulating washers need to insulate the leads from the plate.
mine are both green on the bushes do not forget spacers as will blow fuses and make sure brushes are the correct length. 

This is the exact problem I'm having. It continues to blow fuses when trying to electric start.  When you say spacers do you mean washers?  If so between the brushes and connector or the brushes and the actual plate?  I haven't been able to figure out why this was happening until I saw your reply.

Aircooled RD Tech Help 250cc and Above / Re: Correct jets
« Last post by c50 on June 21, 2021, 07:29:31 PM »
Tony 2T beat me to it!
Aircooled RD Tech Help 250cc and Above / Re: Correct jets
« Last post by c50 on June 21, 2021, 07:28:35 PM »
Choke checked and cleaned looked fine, float heights checked and valves are ok sealing. My patience is starting to run out with this bike. I am waiting for new Mikuni brassware so fingers crossed.

“Looked ok” ?? Did you check it seals fully off?? Also no mention of air correction being checked ?? The air jets are behind the brass blanking balls in bell mouth, you cannot get to them without removing but you can check if they are  blocked! They WILL cause rich running at higher revs if blocked along with a leaky choke.

C50, is there a way to check or clean the air jets?

There are many posts on “removing your balls” !

I have said this many times too. To check if the AC is blocked: pull the two small pipes from the bottom of the carbs out of the airbox. Blow down them, you should be able to with moderate resistance, its a small jet. If you cannot blow down them the AC is blocked probably at the air jets. Even if clear there could be crud in there. I run carb cleaner down through the pipes occasionally when running at idle. If blocked you will have to drill and pop the brass balls out to get to them. And you should replace or blank of again afterwards.

Re Yambits stuff, it’s pattern and from mixed sources with equally mixed quality. Some I have just binned straight away, some I use as a last resort if oem not available. Some doesn’t fit or is wrong for your model. Especially air filters, pistons  and piston rings.
The Piston Broke / Re: Changes to Petrol
« Last post by tractorman on June 21, 2021, 07:24:18 PM »
Thanks for the info Paul.
Aircooled RD Tech Help 250cc and Above / Re: Correct jets
« Last post by tony2stroke on June 21, 2021, 07:22:26 PM »

A pictured guide to get your balls out, and clean the air passage behind.
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