fcr carbs with filter?

naljp123 · Post by **naljp123** » Mon Jan 17, 2005 7:42 am

Greetings everyone, from a new boy on the site. I've been learning a lot about the fzr, and having a few laughs, over the last few months reading this site. Cheers. I'd like to ask a question about fcr carbs and air filters. When I bought my bike last year, a 1989 model, it came with fcr 39 carbs and a slip-on muffler. The guy who I bought it from warned me not to ride in the rain or I'd have problems with the carbs. He said he'd not put on filters because they decreased power. I didn't think too much about it as I usually choose fine days to ride and don't use it to commute. But recently I've been caught out twice in quite heavy rain and both times, after about 30 minutes, the bike has started to cough and splutter very badly. On both occasions I made it home and the next day the bike started and rode fine. Is it usual to put filters onto fcr carbs? If I don't will any permanent damage be done to the engine if I get caught out in the rain?

Post by **Hooligan** » Mon Jan 17, 2005 8:25 am

you can run a ram-air airbox with a filter, or k & n pod type filters. don't take this as religion, there are a few riders here with vast amounts of carb tuning.

dragracer1951 · Post by **dragracer1951** » Mon Jan 17, 2005 10:55 am

You certainly do want to use a filter! Dirt and dust down the intakes will wear the engine very quickly. I'm not a bit fan of pod filters as they upset the intake resonance that the airbox provides and therefore produces a large hole in the power delivery With a little creativity you can make the connection between the FCR's and the airbox Jim

naljp123 · Post by **naljp123** » Mon Jan 17, 2005 7:43 pm

Thanks for your advice guys. As you say, common sense would indicate a filter is important to protect the engine. Unfortunately I don't have the original airbox to play around with. I was just searching the auction site here in Japan and found someone selling BMC filters with adapter set for an fcr carb, starting at about US$30. They've done 3000km on a GPZ900R. I thought this might be a reasonable solution to the problem. If they don't work out I can look for a second hand air filter box and try to adapt it. Would you agree? Nigel

Matt at PSB · Post by **Matt at PSB** » Wed Jan 19, 2005 12:55 am

The FCR carbs are a very sharp edged tool. It is possible that you may have to re-tune them to run right on pod filters if they have beed finely tuned to run on just velocity stacks. Will the velocity stacks alone produce more power? Yes. Can you aford to run without air filters? Well maybe, because you might be made of money. I can't, cause I know the value of money. Filters for my engines please. Matt at PSB

naljp123 · Post by **naljp123** » Wed Jan 19, 2005 9:17 am

Thanks for the post Matt. I've been reading the other threads about fcr carbs and your posts are very informative. Cheers. Well. I've got the BMC pods coming soon so will see how they go this weekend and then start making enquiries about a dyno test. Cheers.

Post by **Hooligan** » Thu Jan 20, 2005 3:43 pm

naljp, i just picked up a set of 39mm flat-slides for my yzf750. at this point in time, it looks as though i'll have to try setting up something with pod filters as i don't have a ram-air airbox. i do however have my stock airbox, so i'll look into what can be done. i spoke briefly with matt at psb (thanks matt!) regarding these carbs and he knows of no kit currently made to adapt them to the stock box. i plan on keeping my exup unit intact. i hope that i don't run into any huge holes in the powerband due to running the pod filters, but time will tell. if i do, the stock mikunis will go back on with the stock box, and the flat-slides will be up for sale. time will tell.

Matt at PSB · Post by **Matt at PSB** » Thu Jan 20, 2005 4:57 pm

Hooligan, Mimic the exact set up the previous owner of the FCRs was using. If still in difficulties than dyno tune them before you give up on them. If the previous owner was running velocity stacks you will need to re-tune for pods. If the previous owner was at more than a 1,000-foot (304.8 meters) elevation difference from your usage location you may need to re-tune to establish a base line tuning. If the previous owner was in a desert & you are in a rain forest at the same elevation you might have to re-tune it to establish a base line tuning. It is not that the FCRs are hyper sensitive to altitude & humidity. It is just that you want to establish a precise base line tuning at the start 'cause the tuning is only going to degenerate as time & distance from the carb set up increases. There are too many expensive parts in your engine's cylinder head to not get a used set of carbs spot-on at the beginning. Even if it runs like a dream with the, new to you, FCRs I still suggest a dyno tuning. Matt at PSB

dragracer1951 · Post by **dragracer1951** » Thu Jan 20, 2005 5:22 pm

<blockquote>Quote:<hr>Even if it runs like a dream with the, new to you, FCRs I still suggest a dyno tuning.<hr></blockquote> Very sound advice!! <img src=http://img.photobucket.com/albums/v209/ ... odpost.gif ALT=":goodpost"> Jim

KontoBoy · Post by **KontoBoy** » Thu Jan 20, 2005 7:55 pm

Hooligan, It would be a shame to put those nice flatslides in a stock airbox. Can I interest you in this brand new carbon fiber airbox? <img src="http://members.cox.net/vineski/Air_Box_1.jpg" style="border:0;"/> <img src="http://members.cox.net/vineski/Air_Box_2.jpg" style="border:0;"/> <img src="http://members.cox.net/vineski/Air_Box_3.jpg" style="border:0;"/> I bought this for my "YZF-750" track bike (well, just paid for it but hasn't arrived yet). It's reportedly brand new. You can see it doesn't have the cut outs for the carbs. It seems a bit of overkill on a track bike with stock Mikunis. I know you're feeling a bit poor right now, but I'd be open to offers. (One sold on ebay for $350-400 last Fall). You getting a tax return this year! Kontoboy

Post by **FZRDude** » Thu Jan 20, 2005 9:11 pm

Ooooooooooooooo....... <img src="http://img.photobucket.com/albums/v209/ ...  There are some who call me........Tim? Director of Entertainment <a href="http://eddieandthecruisersmc.com" target="top">Eddie & the Cruisers</a> 1994 FZR 1000

Post by **Hooligan** » Thu Jan 20, 2005 10:48 pm

yes, i would be very interested in talking to you about the ram-air box. i think it would help solve a few problems... drop me a line at jason at steelewerks dot com. thanks!!

Post by **Hooligan** » Thu Jan 20, 2005 10:54 pm

for your help thus far. there's a good chance that i may need to pick up a few things from ya in the future. i plan on going over the carbs once i get them. make sure everything's running smooth and to make baseline settings of how the previous owner had them set-up. i plan on doing some mild head work with the help of dan rios, another brotherhood member and racer/wrench. i hope to get everything set-up close to good, then fine tune with a bit of time on the dyno. i'll be happy if i don't have any dips or spikes but manage to maintain the integrity of the lower and mi-range sections of the powerband.

naljp123 · Post by **naljp123** » Fri Jan 21, 2005 7:51 am

Hooligan, Congratulations on winning the carb duel. I'll be interested to see how you find them, as I didn't have the old ones to compare with I'm not sure of how performance changed. As other people have noted though, at over 4000 revs they do seem to pull pretty well. My last bike was a Blackbird (sold to buy a car and baby seat) so it is not really a very good comparison as that bike had power to play with in any gear. I'm looking forward to doing a dyno test and will post the results when I get them. naljp. p.s. that carbon air box looks pretty flash

dragracer1951 · Post by **dragracer1951** » Fri Jan 21, 2005 8:48 am

That 750 airbox won't have enough volume for your 1000 will it? J

KontoBoy · Post by **KontoBoy** » Fri Jan 21, 2005 12:26 pm

I'm not an expert, but it has to flow more air than a stock air box, and if it's what's been used on race bikes with 39 and 41mm FCRs I would think it would be capable of flowing air to a 1000 with stock Mikunis. Kontoboy

Post by **Hooligan** » Fri Jan 21, 2005 12:37 pm

i'm not running a 1000 motor, it's the stock yzf750 engine.

naljp123 · Post by **naljp123** » Sun Jan 23, 2005 2:19 am

Received the BMC air filters yesterday so went to check out a couple of bike shops that I thought could fit them and tune the fcr carb. Got a bit of a surprise. Both mechanics I spoke to were of the opinion that I shouldn't put air filters on because it reduced power and was expensive (over US$200 to do a tune and dyno test). They seemed to think that it defeated the purpose of having fcr carbs if you were simply going to tame them by using filters. They both acknowleged that engine life was shortened without them, but said I would be better to change the oil at shorter intervals, which would reduce engine wear more than filters. Found a site on the net that showed how to tune the carbs yourself, but it is beyond my modest DIY skills and I have few tools here. I appear to have three options: stay as is, and enjoy the bike; fork out the money for tuning and take a loss in power, or buy some second hand standard Mikuni carbs plus filter and sell the fcr carbs. Any other ideas?

dragracer1951 · Post by **dragracer1951** » Sun Jan 23, 2005 8:31 am

Well of course they will make less HP with filters than without! But FCR's with filters will make more HP than stock Mikunis Find another shop It may well cost you $200 to get the carbs properly tuned, But then you have a baseline and it didn't take you a YEAR to get it! Jim

Matt at PSB · Post by **Matt at PSB** » Mon Jan 24, 2005 8:05 pm

So let me get this straight: These two shops told you not to run filters on an FCR equipped streetbike cause it would cost $200 to do the set up tuning. So lets see, $1,000 to $1,400 to do a valve job & maybe a LITTLE porting, plus $570 for a Wiseco piston kit, plus $200 in cylinder boring, plus $117.15 for an oil pump assembly, plus main & rod bearing shells at $96.64, plus about a grand to put it all together comes about $3,384.79!!!! Assuming I am not any better at addition than they are we can come to one of two possible conclusions: 1) They do not know how to do what you are asking then to do. 2) They want a lot more than $200 of your money. Keep asking around at other shops with dyno tuning capabilities. Do not get me wrong here, if it was a race bike & you had $3,500 tied up in a spare engine sitting around ready to go I too would be telling you to forget the filters. It is about $200 vs. $3,500 If you purchase FCR carbs new the first set up question that does not pertain to the bike they will be going on is:" Will you be running velocity stacks or pods?" Matt at PSB

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fcr carbs with filter?

fcr carbs with filter?

filters

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BMC filter?

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got the pods!

flat-slides

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yes!!!

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confused...

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