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Post by cycomoto on Feb 15, 2008 8:05:56 GMT -5
I've got a 1980 SR500 and my buddy has 1981 SR500. I want to put a new carb on both of them to make them more reliable and easier to start. We'd like for it to be responsive at the lower end; so we prefer driveability to horsepower. I am fairly technical but my buddy is not. So I am looking for a solution that he can manage. I will install the same carb so that I can help him with the installation of his. What carb would you suggest?
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lurch
Full Member
Posts: 217
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Post by lurch on Feb 15, 2008 9:54:45 GMT -5
HI
I have just ordered this carb from ebay 260211468334
Be prepared to haggle ,I got mine for $250 US + shipping of $36 to the UK
Should work out nice with a bit of tuning
LURCH
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Post by andy on Feb 15, 2008 14:59:01 GMT -5
Hi Lurch,
For the benefit of all,please let us know how this carb performs and equally important the suitability of the jetting it comes with.do you need a bigger manifold and are you running a big k&n.I could quite fancy one but i'll let you test the water first!!
Regards,Andy
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Post by chew652 on Feb 15, 2008 16:30:02 GMT -5
I have the stock carb on mine. One of th POs did his version of the Minton mods on it. It took awhile to get it and the Supertrapp working together and I did put new diaphrams in it but it works great. I am not sure it even needed the new 'phrams. A lot of people throw new carbs on these things but if you haven't made some drastic mods the stocker can be made to run pretty good and it is cheaper than even the cheapest replacement. Also ,if you haven't made any modifications a new carb is not going to give you any more power. I just have a K&N in a chopped up airbox and a 4 inch Supertrapp running 12 discs. I have no idea how much the PO cut the slide but I am running a #330 main(maybe boost it to #340 soon) needle clip one notch fom the bottom and a #20 pilot jet. The smaller pilot jet ended all my hot start problems.
This is just my 2cents,eveyone gets to spend their own money on what they like.
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Post by andy on Feb 16, 2008 5:07:57 GMT -5
Fair comment Chew,nothing wrong with the stock carb if its not worn out and i mean the moving parts not just the diaphragms,if they are they can be a pain.I put a new vm34 on mine [same as stock but non pumper]must admit the downside with moving away from stock can be jetting issues hence the reply to Lurch but the vm34 i put on is so simple mechanically to stock carb.Suppose theres the old saying that sum up all carb issues 'if it aint broke don't mend it!
Regards,
Andy
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lurch
Full Member
Posts: 217
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Post by lurch on Feb 18, 2008 18:24:58 GMT -5
Hi Guys
I'll report back when I get the cafe project put together, just the tank & seat to do & the carb of course but it maybe a while ,as I'm working 16 hrs a day juggling 2 jobs to pay for all the SR goodies ,either that or I'm just a scratting bastard heh heh ;D ;D
LURCH
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Post by andy on Feb 19, 2008 6:20:28 GMT -5
Good 'ol English saying Lurch! I've just started doing nights,good dough,trouble is right now ' I'm struggling to stay awake long enough to go and spend it! Slight change of thread,just bought a polished cam tensioner cover cap of Biebo,looks the dogs bollocks and good price.
Andy
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Post by caferacercarl on Mar 5, 2008 2:31:22 GMT -5
Stock carb is great when set up like chew says,up to 70% power increase at the rear wheel can be handled by that lovely pumper carb and they will start first kick [and last well] next step up is 40mm Dellorto [price wise] then Mikuni pumper, then the expensive but lovely Keihin FCR for the SR builder with a good budget, regards Carl.
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Post by fastfred on Mar 5, 2008 14:15:08 GMT -5
Just put on a 36mm VM series Mikuni, starts first kick every time.
Ebay or Thumperstuff.com.
The original carb is too complicated and when the diaphragm is broken, you can't get parts for it.
Fred
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Post by cycomoto on Mar 6, 2008 19:23:28 GMT -5
OK. So I have decided to pony up and go with the FCR carb for my 1980 SR500. I have a pair on my 2004 Bonneville and they transformed the bike. So with no engine modifications, I would expect the 39 is a better choice that the 41. True? Should I go with a choke or no-choke set up? Any suggestions on where to start with the jetting? Is it possible to run the stock airbox (with K&N filter) with the FCR carby? Are different manifolds required? I would like to run the stock (quiet) exhaust because, ultimately, this bike will be rigged to a sidecar.
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Post by caferacercarl on Mar 10, 2008 2:33:05 GMT -5
The diaphragms are easily available,I have 5 of each in stock, its a great carb. the fcr is best as 39mm on fairly stock [ 3hp more than 41mm under 6,000rpm] but you can get a K&N filter adaptor from Sudco, then run the biggest pod you can, RU1770 fits, you will need a better muffler though just to jet it right, the bigger the muffler diameter the better the noise absorption, eg, 4inch by 18 inch with a 1,7/8 perf core and stainless wool packing is 92db at 2,000rpm, thats legal!! regards Carl.
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Post by stevec5000 on Mar 29, 2008 23:48:14 GMT -5
I replaced the old stock carb that I couldn't keep working anymore because all 3 of the rubber diaphrams were bad with a new Mikuni HS40 that I got at the local Harley shop for about $100. They sell them as upgrades for Harleys. The only jetting change I had to make was to change the pilot jet from 15 to 17.5 and it works great. It starts better now too. They normally come with a 17.5 pilot jet but mine had a 15 for some reason so I changed it.
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Post by caferacercarl on Apr 1, 2008 2:56:51 GMT -5
Does everyone want the part numbers for the diaphragms? if a shop says they don't exist go to another shop! or, fit something with a pump, it is a four stroke single after all, ask curly on this forum, he has seen the whole thing on a proper dyno and has bought a dellorto from the states, $150 on flea bay!!! after 3 decades we have these things pretty well worked out now.
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Post by stevec5000 on Apr 2, 2008 7:38:57 GMT -5
>Does everyone want the part numbers for the diaphragms?
No, they don't hold up very well here in the desert heat so it's
better to use a design that doesn't have them.
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Post by chew652 on Apr 2, 2008 18:32:05 GMT -5
>Does everyone want the part numbers for the diaphragms? No, they don't hold up very well here in the desert heat so it's better to use a design that doesn't have them. Yeah ,lucky there are no deserts in OZ  Thanks for the offer Carl ,I found mine online last year at this site. www.yamahasportsplaza.com/pages/parts/viewbybrand/default.aspx Some one in a cooler place might want them  |
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