Carb settings (pod/cone filters instead of airbox)

[Gazaragi]

Hi All,

I'm hoping to get my R65 up and runing and ready for an MOT this weekend and have been struggling to set up the carbs.

There's no airbox on the bike so I'm runing cone filters for now and I'm runing into a few issues.

The bike is running, but the revs are not falling quickly.

I've ordered all new cables and return springs and will fit these and check that the handlbard grip is not gummed up. I'm also replacing teh rubber coupling betwene carb and head. Which may help solve the issue, but have the following questions - I'd aprecaiate any help you are able to offer.

Runing pod/cone filters and no airbox...

Has anyone else done this?
Did you need to change from the standard needles and jets?
If so what size?
What settings did you use as a base?

Many thanks!
Gareth

[D Mann]

I think I read an article on Snowbums' site  http://bmwmotorcycletech.info/index.html   If I remember right you start with the base settings in the book. There was a problem with the fuel foaming due to vibration from lack of support, you need to change to more flexible fuel line. Check his site he had all the info.

[montmil]

The bike is running, but the revs are not falling quickly.

Your high idle / slow to return to idle problem could be something other than a fuel issue.

Confirm you have about 1mm of slack in the throttle cables as measured at the adjustment ferrules on each of the Bings.

The bob weights inside the ITU -bean can- could be sticking which can cause the "slow to return" complaint. May be time to take a look. Some owners will spray something like WD40 into the can. This may resolve the issue for a short time but eventually the WD will mostly evaporate and leave behind a light, gummy residue that will contribute to the return of the original problem.

Also, valve lash has a bearing on this problem. Check and or set valve lash. Check timing while you're at it. These items can modify idle performance.

Hope these suggestion prove helpful for you.

[Gazaragi]

many thanks for the speedy replies and advice. The speedy replies. Lot's to think about. Thus starts the process of elmination. *crossed fingers*

[marcmax]

I had an issue of the revs not falling quickly enough and just knew it was a carb issue.   Once I adjusted the valve properly it all fell into place.  

[Luca]

Lots of good advice here.  I'll add a few points:

Valves get adjusted with the engine cold (let it sit overnight), carbs get adjusted with the engine hot (15 miles of riding is probably sufficient).  Carburetors are also the very last thing you want to adjust.

If you adjust the carbs before the engine is fully warmed up, you will probably end up with idle stops screwed too far in and/or mixture screws unscrewed too far out, both of which can cause high idle issues.

Base settings are just some rough points to get an engine running so that you can warm it up and tune it.  After your initial tune, ride it around a bit and have a look at the spark plugs to get an idea of the mixture quality (lean/OK/rich).  Could be that you won't need to make any changes.  Pod filters on their own won't really make the engine breathe that much more.

[Gazaragi]

Good new...well partially.

New cables, new rubbers on the brass wear in the carbs. New rubbers between carb and engine. Float heights checked and set.

The bike is running reving freely and climbing and descending the revs now as it should :-)

However, when using the carb balancing machine it shows that one cylinder is dominating at low revs. Both are firing fine, but it's not a great synch. Some head scratching done.

Will try putting the proper airbox on, if now better, I'll look at the valves (I take it by valve 'lash' people mean 'clearance'.

Thanks again all.

[steve hawkins]

That is the point of doing a carb sync, its at this point you have to adjust the carbs so that they idle the same and when you operate the throttle, they both open at the same time.

So first you set the idle, using the idle stop screw, and then you set the cable lengths of the throttle, by using the adjust on the cable at the carb end.  You have to get them exactly rev up exactly the same by blipping the throttle and then holding a higher rpm.

You are very close.  I use pod filters and standard jetting. No problems to report.

Cheers

Rev. Light