I got this R running. It is an 86 with port and polish, paul turner "race" pipe, and a taper bored carb ethe break in process. I can't get it to idle with the taper bored carb. I put my stock carb from my 88 on and it idles/runs good. The jetting is off, but easily fixed after a few heat cycles. When a carb gets bored, does it lose its ability to meter fuel properly on the idle circut or what? Everything inside the carb is clean and looks servicable, and it runs as good as I can expect after all the work, but it just won't idle.
background on the machine is as follows. I just got it last week, got it home to find leaking crank seals and way worn out top end. Took it apart and dropped it off at machine shop. I got it back together today. The top end has been professionally ported and polished and uses the CR250 Wiseco piston. The machine shop is super and bored the cylinder, chamfered the ports and gapped the rings. I had to drill the lube holes in the piston for the exhaust port bridge. The head has been milled and rechambered for race gas and a thin head gasket. I am running the stock head gasket and premium pump gas which has not been a problem.
At this point, I am content to run the stock carb as this is my wife's ride and it seems to have good powerband down low with a lot of promise up top. Won't know how much until final break in.
Any help here would be appreciated, or if you want the carb, let me know, might make a good paperweight.

 

You are leaving too much info out. What size pilot jet do you have, where is your airscrew set, have you set the float level and most important what brand and size is the bored carb. The carb will not lose it's ability to meter fuel, it's just that the air to fuel ratio will be of due to the higher air volume.

I just got through this myself so I could help with a little more info. Most likely you will need to change the pilot jet and dial in the airscrew.

 

I am afraid I have wasted your time. When I first got the machine, it had so many problems,(leading crank seals, bad top end, etc) that I didn't change out the fuel in the tank with fresh premix. After got it running, I realized my lapse in judgement and added fresh fuel. After reading your post, I went out to verify that I had the stock ilot (48) with a 165 main. I had originally cleaned teh carb, but when I removed the pilot, there is a piece of crap in the orifice. Rookie mistake.
It does seam to me that the only benefit of the tapered carb will be more top end at the expense of the bottom. Since this is my wife's ride, I am content to leave the stocker on there and just jet it properly. Any thoughts on this? The air box lid and all snorkles have been removed and it runs a UNI foam or a K&N with filter cover depending on conditions.

 

Increases in carb size are indicated in a loss of low end throttle response and an increase in upper RPM range power. To the extent of either is dictated by how large of an increase. Taper boring and D shaped boring are done in an effort to offset the decreased air intake velocity at lower RPM's, while still allowing for the benefits of increased air flow.

You might consider bumping up the compression some(as much as your wallet will dictate) to get the low end back, and you'd have all around more power...just some thoughts.

 

The machine is set up for a thin cr style head gasket for use with the milled head and race fuel. My machine shop measured the cc of the head and determined that the stock (thick ) head gasket would work with pump gas. Kind of like switching domes.
I want to get the machine broken in and jetted correctly before I try this bored carb again. I was doing some break in runs today (putting a few heat cycles through it) and it runs really nice. I guess I will leave it alone unless she wants more out of it, at which time I will try out the bored carb or maybe just throw a 38 mm air striker on it. They seem to carburate a little better than the stocker. Maybe it is just me.

 

I'm a real BIG fan of Air Striker carbs...the idle circuit is MUCH better on them than the stocker PJ carb is. The throttle response is pretty snappy too. With a 35mm A/S it can be massaged out to near 37mm's. This would retain near stock like throttle response with greater top end. A 38mm A/S would work as well, but could be just a tad spongier.

Good luck!!!

 

I have the 38 Air Stryker on my ESR 310 and it is really nice. I haven't done a plug chop in top gear on this new bike yet, but I do feel it is going to be lean everywhere. I will go up one on the pilot. I get the carb set at idle and air screw adjusted fine, but it bogs and is unresponsive when I wick the throttle. I am pretty sure that is a lean condition. Once I have that sorted out, then I will do a plug chop for the main. I know that you are supposed to work out the mid range before working on dialing in the main jet, but I have had better luck getting the main in the ballpark then working out the needle. Fine tuning the main jet after that has always been easy for me.
Thanks.