kehein 41mm fcr vs mikuni cv vs dellorto - thoughts

[klr_gil@yahoo.com]

Sounds like cutting off the top of the airbox is a good idea, let the bike "breathe" a little easier... But how do you remove the airbox to do the modification? I've been in the garage, trying to figure it out, loosening a bunch of stuff, but no luck getting it clear...Do I have to drop the sub-frame? Gawd! I can hardly wait for that service manual!! thanx, Gilbert

[stfontaine@hotmail.com]

Take a look at this web site http://www.angelfire.com/mo/motormark/mikescarbmod.html I think you will find your answer there ! Stephane Fontaine, A15

--- In DSN_klr650@y..., klr_gil@y... wrote: > Sounds like cutting off the top of the airbox is a good idea, let the > bike "breathe" a little easier... > But how do you remove the airbox to do the modification? I've been > in the garage, trying to figure it out, loosening a bunch of stuff, > but no luck getting it clear...Do I have to drop the sub-frame? > Gawd! I can hardly wait for that service manual!! > thanx, > Gilbert

[thesquasher@hotmail.com]

Don't cut up the air box, just remove the side cover. Or you can do the cover mod that I did. http://groups.yahoo.com/group/DSN_klr65 ... erformance% 20mods%2C%20results/Mods/extrair.jpg I put foam(oiled) over the opening as a pre filter to keep most of the dirt out. If you mess it up a new cover only costs around $18. A new air box is most likley over $100. I think most of the restriction comes from the screen that sits between the filter and the carb.

--- In DSN_klr650@y..., klr_gil@y... wrote: > Sounds like cutting off the top of the airbox is a good idea, let the > bike "breathe" a little easier... > But how do you remove the airbox to do the modification? I've been > in the garage, trying to figure it out, loosening a bunch of stuff, > but no luck getting it clear...Do I have to drop the sub-frame? > Gawd! I can hardly wait for that service manual!! > thanx, > Gilbert

[Ted Palmer]

(Gilbert) klr_gil@... wrote: [...]

> But how do you remove the airbox to do the modification? I've been > in the garage, trying to figure it out, loosening a bunch of stuff, > but no luck getting it clear...Do I have to drop the sub-frame?

Sort of: you can loosen the carby tube, muffler, electrics, and subframe, then pivot the subframe on its lower mount bolts. Mister_T

[Steve Green]

I have installed Kehein FCR 41 mm in place of Constant Velocity Mikunis on my 99 KTM 640 LC4 and my 99 Ducati 900 SS. I also have Dellorto 38 mm round slides on my R90S which are similar carbs, sharing many of the same attributes as the FCR i.e. smooth bore and accelerator pumps. Dellortos are very popular with the European Thumper crowd. In Europe the KTM crowd use an "oval bore" Dellorto which is supposed to be very good. I have no experience with Mikunis other than the stock CV type. My KLR remains stock in the carb department. My 92 Ducati 900 SS uses down-draft type FCRs, and my 99 KTM 640 LC4e side-draft type FCR. (Both down and side drafts are the same basic carb from what I can tell but their floatbowls are oriented differently to their venturis.) Based on my experience here are some thoughts on FCRs, CVs, and Dellortos. FCRs are great carbs, easy to work on, carburate well, and flow more fuel/air than CV carbs of the same size. There is a definite power gain, and the accelerator pump gives quicker/crisper throttle response. They are sold by Sudco and others as complete kits which are fairly easy to install, but not perfect due to slight cable and fitment issues. They run abround $400 for the kit (one carb). However, they are physically large carbs thus can be a very tight fit in some applications i.e. the KTM LC4. Their throttle linkage is exposed to the elements more than some carbs like the Dellortos. This may possibly lead to dirt interfering in their operation and also entering the exposed throttle cable. I have not had this problem but I can see it as a possibility in very muddy dirty situations or over the long run. In conclusion, I think that the main advantage of the FCR carb is the smooth venturi at full throttle since there is no butterfly valve or shaft interfering with air flow. The other main advantage is the accelerator pump and its benifits. I do not think that the flat slide is any big deal though. My 99 KTM LC4 is working just fine with the FCR in the dirt and on the road. I am happy with it. BEWARE of the following with the FCR: The KTM LC4 FCR kit comes with a screw on adapter for the engine side of the FCR. This adapter has very fine threads and has been known to strip out the carb body threads if it is not properly tightened and fixed with Loctite. The pressure fluctuations on a large bore thumper are great and can eventually rip these fine threads right out. So be sure to tighten this piece well and Loctite it too. Based on my R90S Dellorto experience: I would like to try the more COMPACT Oval bore (or round bore like the R90S) Dellorto. This is also a smooth bore (non CV) carb. It has the accelerator pump, along with an enclosed cable and straight pull slide. It may be the best choice for DS riding. (The straight pull cable could pose a fit problem in some applications.) It could be a problem finding a kit that comes complete. Hope this all makes sense and is of some help. Steve G in Colorado

--- In DSN_klr650@y..., donshore7@h... wrote: > I would like to here from someone who has actully installed a slide > carb. Either a kit or on there own. Is there a enough gain to justify > the money and work? If so what parts and or kit did you use? Any other > suggestions such as exaust airbox mods ect. would be apprcieated. > > Don