Topic: Keihin CR carbs and your starting procedure

[Terry in Australia]

What size needle/main jets combo's are you guys here with 31mm CR's on 836cc engines using? Also, I'm going to use a remote idle screw assembly, the stock CR setup is no good on a CB750, is there an "off the shelf" item available, or do I need to make my own? Cheers, Terry.

I'm using 30mm velocity stacks, 130 mains and YY7 needles (one clip position leaner than middle). The open stacks and 4 into 4 open meggas can take quite a bit of fuel.  If you're running K&N's and a four-into-one pipe, you might want to try 125's to start, and stick with the YY8 needles.

Thanks Doc! Cheers, Terry.

This would work
http://www.ebay.com/itm/1997-HONDA-CBR600-CARBURETOR-IDLE-ADJUSTER-SCREW-CABLE-KNOB-/330645970124?pt=Motorcycles_Parts_Accessories&vxp=mtr&hash=item4cfc091ccc

Thanks mate, I've got something similar here but the threaded end is smaller than on my CR's, I'll pronbably just make my own. Cheers, Terry.

 

[Terry in Australia]

link
http://www.jetsrus.com/individual_parts/018_778_su.html

45 bucks for a screw? Oooer, last time I paid 45 bucks for a screw she showered me, dressed me, and kissed me goodnight!

Its good to see our $45 dollars going a little further in the current financial climate....

Nah, that was in 1977 Mick, almost a week's pay for me back then, but well worth it!

[brandEn]

Just wanted to bump this thread to see if anyone else wanted to chime in...

[vfourfreak]

Not quite over the counter CRs, but I remember watching the Honda Britain works F1 bikes in the paddock at the Ulster GP back in the day ('78 or '79). For cold starting they had made up light plywood boards with four holes about half the diameter of the bellmouths. They held these up against the bellmouths and push started. The restricted airflow gave all the choke they needed without using ticklers or a choke circuit. Simple but effective even if it was a bit fiddly to achieve a good bump start with a mechanic holding this little board. However if you have a kick start, single person operation should be possible.

Kev

[bear]

This is probably not all that relative to this discussion, but that's never stopped me before.
We run methanol so our starting procedure is a little different.
The old girl can be very hard to start cold on A.
So we use a squirt bottle of petrol, hold the throttles wide open, give each bell mouth a squirt, shut the throttle and give it a kick.
This usually works a treat, usually.
One of the problems with methanol is that if left in the system it will soke up moisture from the air and it becomes a sticky gel. This often results in the float needles sticking,if the system is not cleaned thoroughly, causing the carbs to flood. A problem in it's self, but combined with the bikes tendency to backfire through the carbs if the throttle is snapped shut has cause some pretty interesting situations.

Cheers,
Brian

[ampsrampstramps]

I've got 29mm CR Specials on a 1980 DOHC CB750F and I don't use the choke at all. Just hit the starter button and follow it quickly by a little throttle and it fires up first time. At first I would open the throttle a little before hitting the starter, the bike would take forever to start. I also had the choke open a tad and it didn't help either. After putting in a richer needle and replacing a bunk spark plug it fires up first try with no choke. I have to keep the throttle open slightly for 30 seconds or so once its running or it will die. Looking into air jets or slow jets as we speak.