1981 XJ650 maxim intake boots YICS

Looking on ebay and amazon for the intake boots some say they will not fit, if its a yamaha head but will fit if its YICS and some say they are junk ..any advice guys .... my old ones are not cracked on the inside but they may have been mixed up over the years regarding the sync port locations

 

Contact @chacal either through a conversation here or email info@xj4ever.com
He has the correct non-junk intake parts.

 

thanks

 

xj4ever boots are 50 bucks each plus tax and shipping....i will either leave the ones i have on now or go with amazon, at least i can send them back ....

 

The ones on Amazon are total junk. Waste of money and time. Chacal used to sell them until we all started seeing internal failures. A failure type that IMO creates the possibility of debris from the boot entering the combustion chamber and causing a very expensive repair.

If your budget is that tight then you can repair the boots you have.
Clean and degrease them thoroughly. Then (wearing gloves) use black oil-resistant RTV to fill in the cracks and cover the surface of the boots. You can smooth the surface of the RTV by wetting your finger and going over your work.
That method is what we all used before replacement intake boots became available again.

 

Mixing them up won’t matter, if not cracked then why are you replacing?

 

On #3 cylinder the vac connection is pointing down to the right, almost touching #4.. swapping them 4 to 3 puts the line up off, carbs would not fit...been that way a long time ..so can not remove cap to do sync, they must have been replaced before, long time ago rubber is hard... Decided to go ebay if they are junk i can send them back no charge...

 

Plus eliminating the boots... i have a big problem that i can not solve, surge on highway after 1/4 throttle ease back to 1/4 and its ok... had carbs apart/cleaned passages for the third time, found nothing.. ready to go back on... valve clearance ok... pulling away 1st 2nd 3rd through gears, flat spot.. feels like fuel on then off ?... this is the bike that never ran for 21 years

 

That is strange. Maybe remove boot #4, wrench off the vacuum cap of #3, put a vacuum line extension on #3, add a straight vacuum connector to the end, cap off the connector, reconnect boot #4. May not be pretty but would allow vacuum syncing your carbs.

 

Thanks ... boots on the way.. looking at the rubber up top no tears bit out of shape

 

Did you remove from carb and slightly stretch all round while holding up to a light source?

 

That is odd, there are different intakes for YICS and non-YICS motor. I have no idea if they are interchangeable but you must have a mix of intakes I'm thinking! Hard to say what PO's did over the last 40+ years.

 

Yes checked the rubber diaphragm several times stretching for cracks ..none .... yes mix of intakes for sure interchangeable yes, but the vac ports must be different place... getting set off ebay cheap 22 bucks with gaskets.. made in China .... my 650 has the YICS badge in the cover but who knows its life could have a non YICS head.....

 

How’d you know what to order then? Got a pic, we can confirm!

 

Even then all of the vacuum ports should point straight up. The non YICS boots are at a different angle horizontally, but all have the vacuum ports at 12 o'clock.

 

The YICS head has a distinct manifold at the rear of the head with blocking bolts at either end. The non-YICS valve cover does not fit onto the YICS head.

 

Any pictures of head not sure what you mean blocking bolts at either end

 

Thanks for the picture, i see now... no i dont have the YICS head, production date on my 650 is 6/80.... back to my carbs, i will bring the float level up 3 mm so its close to the bowl gasket, get rid of the mesh screen above float needle couple have splits ... i have the brass in line filter that should do...

 

Cool, the ones you ordered should all be the same then. The YICS motor use two left and two right, non-YICS are all the same. Len's catalog confirmed that the same manifolds that are used on non-YICS are the same as the right two on a YICS motor which makes me think you have some upside down or from a YICS motor all mixed up.

 

Could i be getting the wrong ones getting two right and two left

https://www.ebay.com/itm/1650092599...efaultOrganicWeb&_trksid=p2047675.c101224.m-1

 

Based on the description and pics those are the wrong ones, you’ll end up with the vac nipples in the wrong spot like you currently have.

 

Thanks.. i see that now... i will stick with the ones i have now, and do what huntchucks said fit extension the #3 cap

 

Do the carbs actually fit correctly doing that? Like without any vacuum leaks?

 

Yes good and tight no vac leaks just the ports different... Bit of a fight fitting the carb to airbox boots .. working on that... Been like that for years

 

Ummm.....intake manifolds have compound curves: INWARDS, towards the centerline of the bike (so #1 and #2 curve "to the right" looking from the rear of the bike forward, and #3 and #4 curve "to the left"), and they also curve UPWARDS (towards the sky, or in other words, in the direction that the vac nipple is pointing).

Fitting the incorrect LH manifolds onto the RH side will maintain the correct "inward/towards the centerline of the bike" curvature, but leaves the manifolds curving "downwards" (towards the engine). The center-to-center spacing for all the carb throats will still be the same, but the carbs will be "tilted" down, and to the right, by a somewhat significant amount.

 

I would NOT trust that set. Simply because it says “fits ‘81-83 xj650 .......
‘80-‘81 are DIFFERENT THAN ‘82-‘83.

 

Been like that for years and isn’t running right. Your fuel levels in the float bowls will be off, as per Chacal’s post.

 

Carbs fit perfect how's this look.. had to fit inner boots to airbox first it's all 42 years old.

 

So should the carbs be level, looked at other 650s and they all tilt .. I had no problem fitting carbs all lined up,.. the airbox lines up ok .. the bikes on the center stand so the rear wheel is up in the air making it worse,, could that tilt be my bogging down problem

 

Found this youtube video mint xj 650 ..8.20 minutes in shows the carbs and they are tilted..... getting back to the boots anyone found my correct boots on e bay

 

If it were me I would get the correct manifolds, you already committed to buying a set why not get the right ones. Looking at your pic I can see one is covered with JB weld, plus you can see that the right ones (3,4) are lower then the left set since they are on upside down and do not "curve out and up" correctly. I cannot imagine the boots are tight having them not line up and the carbs would most likely end up at the wrong angle.

The carbs will have a little tilt to them when installed correctly.

Why not buy them from Len and know you have the correct ones that won't fall apart in short order? I know they're a little more expensive but its a quality part and the service is second to none. I'll dig up my pic of my aftermarket intakes after a few days.

Good luck on eBay, I poked around and there are many that are listed incorrectly both in description and pics. If I was attempting it, these look correct by the pic but I wouldn't guarantee it as the description again is wrong on the years and the OEM part numbers listed.

https://www.ebay.com/itm/323365273599?fits=Submodel:XJ650|Year:1980&hash=item4b4a127fff:g:ZVwAAOSwMDJgG2mH

 

Thanks for that info... used superglue to fill the cracks turned grey lol ..i sent a couple of members a note on the boots they bought for there 1980 xj. see what i get back... the last owner rode the bike three years like this until he parked it up, said it ran ok...But yes the boots are wrong would this cause my bogging down problem?... no vacuum leaks before i pulled the carbs last run out ..went through a can spraying.... clamps good and tight.... that ebay link you sent seems the right boots....... i have $1150 into this project bike so far ... yeah i know it never ends lol

 

If the carbs aren't sitting at the correct angle to begin with then the fuel levels won't stay within the range that they need to be in while riding.
So yes, that is a potential source of your bog. Fuel starvation due to low fuel level in one or more float bowls.

 

Decided to take it on test ride... bloody hell no carb problem, ran perfect so my second carb clean did the trick must have missed something ..could have been the needle mixture passages ...what else did i do, ah yes up the fuel level 3mm... made sure the air filter boots were on tight no leaks..... all plugs tan color mixture 2.5 turns out.... thanks for all the help guys... next job i need to replace the side stand frame bracket

 

And I’m working on getting that for ya

 

Great thanks

 

Well was i wrong should have gone on longer ride.... today i took it on its maiden voyage to speak sixty miles ten freeway, rest canyons /two steep grades pulled like a freight train steady throttle ok .. now winding it to full throttle it pulls all the way through the slight surge 85 mph.+.. so i still got a bit surge ... came home and re set mixture, seems to idle smooth at about 1.5 turns each carb.... Wrong..back on road again this made the surge worse, so back home again lift tank turned 2.5 out each carb.... re test back (dam a bee stung me on the knee...jeans lol)...to where i started when i first went out...So i will be getting the right intake boots like you guys said

 

going off the part number these boots are for the 80/81 model 4h7-1358602 right .. 5g21359601 left... found a set on e bay contacted seller, port location

 

Measurement from float bowls is off from fins to block gasket.. carb 1 is 2-1/8th carb 4 is 1-7/8th. picture showing how i did it

 

To all thats following this post i got it sorted ..after ordering the wrong boots they came in the mail yesterday ....on my 650 # 3 and 4 were wrong they were tilted down, what i did was use #1 and 2 of the new ones i got stuck them on 3 and 4 ... all things straightened out with vac ports up top.

 

There is a reason why we recommend buying most parts from @chacal.
He almost never sends the wrong part, and when he does he fixes the problem quickly.

 

Paid $22 bucks for these wrong boots only used two of them/gaskets/clamps ...lets see how they hold up to the gas additives.... got two spare if anyone needs em

 

looks like i made a big mistake getting these boots. now have vacuum leak right where it bolts to the head..... got to get the 1980 model year intake boots

 

Last chance lol... going to make thicker gaskets and use RTV ..seems like a lot of 650 owners recommend RTV ..could pull there carbs off blindfolded not had em off so many times...

 

got some fel-pro gasket today it was 31 thou thick before compressed... on 1 and 2 the rubber ring was as hard as the outside, straight edge showed it was not level... used flat tile and 500 wet/dry grit paper got that sorted.... did the same with the other two (china junk) boots the rubber ring was not above the boot flange not level surface ... did not use RTV... Passed the garage test with spraying carb cleaner.... have yet to road test

 

Still got the surge after 6k ...using sea foam now ... used propane no vac leaks, spark plugs not rich or lean......runs perfect at idle hot/choke cold, runs perfect at 65mph... surge 6k and up, it will pull through surge to red line. notice it at steady 70/75 mph... giving it full throttle and backing it off ...making sea foam do its job (i hope) have to do a longer run and do a plug chop


The carbs on these bikes have three circuits - three paths by which fuel/air can make it to the engine. There is the enrichment (a.k.a. "choke") circuit, the pilot circuit, and the main circuit.
Enrichment circuit - manually controlled by the "choke" lever. This circuit is used to enrichen (add more fuel) to the mixture to make starting and running a cold engine easier.
Pilot circuit - This the primary source for low-RPM fuel/air supply.
Main circuit - This kicks in at higher RPMs.

So if the pilot circuit is clogged or otherwise not working correctly, then that can be masked by the enrichment circuit providing the extra fuel that the pilot circuit is *supposed* to be providing.

There is also an adjustment on the pilot circuit to adjust the fuel/air mixture (rich/lean). If the pilot adjustment was severely lean, then that would be just like having clogged pilot jets.

 

This is just a thought. By surge do you mean rpms go up but speed dose not increase. If it is doing this it might be a slipping clutch.

 

No rpms do not go up clutch not slipping