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FCR40 from a CRF

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I am in the middle of installing an FCR40 from a CRF450. I am using the CRF throttle and cables since the seller was nice enough to include them. So far the installation seems pretty simple. I had to notch the throttle cable bracket to clear the frame...but it appears I will be able to retain the push and pull cables.

My question is this. What is the purpose of the third cable that comes out the side of the carb above the throat of the carb? What should I do with it?

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hot start.you wont need it with electric start.remove the cable,put the plunger back in with the spring over and the black fitting to hold it in.

find a cap that snaps on the hole and your done.

the red caps that come on braided brake lines work perfect.

drz475supermoto074.jpg

also,move both motor mount plates to the left side of the frame.your cables will have the clearance they need then.

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I had my eye as well on a FCR off a CRF450R on eBay. Any reason it shouldn't work well is the original muffler ? - How complicated is the task installing it :banghead:

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yep,they are actually 41mm.

to much carb on a stock motor drz especailly with a stock muffler.

this conversion doesnt work with the drz air box.

not offroad at all.

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Notes to anyone planning on installing this carb on thier S.

The carb can fit with the push and pull cables but you will want to use the entire throttle cable and assembly from the CRF 450. It is an extremely tight fit. I will probably remove the return cable and saw that part of the carb off to make more room for working on the carb.

Burned does not recommend this carb for the 400 or the stock air boot. I am bucking his advice at this point only because the my bore and stroke kit is in the mail and the CRF airbox is on my garage floor...but I don't want to modify the air box with the CRF boot until after my next dual sport ride...and I have some time to figure out a way to seal up the CRF450 boot modded box for dual sport riding. The boot has to stretch a bit...but will reach the carb. The clamp could be tighter...the stock boot is actually designed for a carb with a bigger mouth then the FCR40 if you can imagine that. I did go ahead and remove the back fire screen as I noted the CRF450 box did not have one anyway.

Getting the tank on the bike with the FCR40 was another challenge. The vacumm nipple on the S petcock would not get past the TPS sensor on the FCR...so I had to remove it. Can't use it anyway since the TPS and the DRZ wiring harness are both female plugs. Getting the tank on is still difficult but not impossible after removing the sensor.

I bought a nipple for vacumm to operate the petcock from the intake port...but the clearance is pretty tight. It might work with a tight 90 degree hose...but it will not be easy to work with. I recomend looking into using an E petcock with this conversion.

I am still waiting on a couple of my jetting parts for this combo...but I did go ahead and fire it up. Idle is not right since the proper jetting is not in place...but I did note that it revs much quicker then the BSR. I have not ridden it yet...but I will give you feed back when I do.

Conclusion on the installation? Difficult...but not impossible. Be prepared to adapt and overcome. Don't do anything permanent to the old parts until you are satisfied that the outcome will be acceptable. At this point I can back the whole thing out with no ill effects. (except for the back fire screen)

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double check that the the air jet ports in the carb actually align with the port in the drz boot.

also keep in mind that the results of the set up your doing will be less that optimum.im sure it will work better than a bsr,but you will be leaving alot on the table.

even using the pre 05 crf air boot is leaving some on the table.

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also,move both motor mount plates to the left side of the frame.your cables will have the clearance they need then.

Burned, Dammit your good :banghead:

You just solved my problem without me even telling you I had one.

I have just installed an Edelbrock, and the only problem I had was running the throttle cables past the head steady. I have rotated the carb a couple of degrees and put the cables between the plates. Now I can do it properly.

Cheers Neil.

:banghead:🤣🤣

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The S boot does not have that provision. It is a wide open mouth all the way to the carb.

I bought the 03 airbox from the bike the carb came from. But I do have an 05 boot from ron ayers. Since I intend use this bike in both forms (SM and DS)...I need to find a way to make it perform acceptably for both modes....even if it is a cheesy tape up job for the increasingly rare occasions when I get to go off road...at least until I can afford a second bike. :banghead:

Don't have the time to engineer that now since I have to be ready to ride DS in a couple of weeks. If I cannot get satisfactory performance from the CRF carb before then...the BSR will have to go back on...hence...I will cut nothing untill fully commited.

And as always...thanks again Burned! :banghead:

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The S boot does not have that provision. It is a wide open mouth all the way to the carb.

i forgot about that.that may end up causing you some jetting problems.

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I only need acceptable performance until I get a chance to do it right. Seems like it should be doable.

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I am still not jetted 100%. The bike is still obviously lean...but even with the corked up exhaust this carb makes considerably more power then the Mikuni. I have had a struggle with the off idle bog...but I have figured out it is due to the lean condition. I will try and get a 175, 180 and 185 jets tommorrow.

Also...I can screw the fuel screw all the way and only make a modest effect on the idle. I guess that means I should consider using a smaller pilot jet. Correct?

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