Looking for 1979 Honda CT90 carbureter rebuild kit

[longbowelk]

I am new to this forum. Also, I am new to the Honda motorcycle 2 wheels. I am looking for a Honda carb rebuild kit for my newly purchased 1979 CT90. The ones I find go to 1977. My research says to stay with OEM but I can't locate. Anyone have a source? If not, I may have to try one of the best after market sources.
I have a lot of questions on this Honda but will post separately. Thanks for any help, Alan

 

[b52bombardier1]

Dr ATV is my candy store for these bikes:

DrATV BRAND CARB_KIT CT90 "78"TO"79" 7/20R (43I)

The Doctor also has an OEM sort of "Keyster" rebuild kit for a 79 but it shows as temporarily out of stock.

Rick

 

[ktheake]

Try looking up a Honda parts store and write down the parts and numbers you need - I try and have a seal kit for the bowl and pettock as well as others so they usually offer a kit then I buy a screen for fuel . Know if you need an air filter - then I open the carb up and hope that jets are usable - able to clean and that should get you back running well . Or you can wait for the kit mentioned above .
You didn't mention if or how it's running - if it's running ,you have time

 

[longbowelk]

The cycle was cranking and running. Once warmed up it idles good. It has a hesitation when shifting from 1st to 2nd. The last owner had put in line gas filters. One had a lot of rust. The air filter looked to be original and was half gone. Squeeze it and it just crumbled. After seeing this I was surprised it even runs. Overall the bike looks in good shape but still needs lots of upgrades. I am replacing the battery, cleaning and resealing the tank, replace fuel lines, and rebuild carburetor. The bike only has 550 miles on it. There are issues with the lights. Headlight stays on and I don't see a switch to turn off. The blinkers don't work. I'm not planning on driving on road but it would be nice if everything works. I will probably end up seeking help from a dealer or another qualified mechanic.

 

[ktheake]

That's helpfull - so get an air filter and a simple seal kit from Honda . if you take a look at the schematic it should show you the seals included - you may need a carb to intake gasket and there usually is a seal/ o ring at the insulator . I usually find a fuel filter/ screen is needed as well - Then when you have those pieces - open it up . If your not comfortable with cleaning and rebuilding the carb - by all means have someone assist / professionally .

 

[-Nate]

KYSTER makes good quality kits , I get mine from Western Honda, best price and always in stock .

Before you touch the carby you need to adjust the valves to .002" with the engine stone cold and the "T" mark on the alternator rotor lined up ~ this is very important as the valves close up over time and cause most of the running problems .

If the carby is original it'll have the model number faintly stamped into the smooth edge of the flange .

Maybe SUDCO in So. Cal. will have the kits in stock .

Don't expect any shop or Honda dealer to understand how to work on your bike ~ they don't much see the older bikes .

One , in Glendale California is very good on the older bikes .

 

[longbowelk]

Ok, I ordered several kits from about 3 sources. All supposedly for a 1979 carb. I finally got it off and tore down. I'm thinking this is not original on the bike. It looks like it may be for a 1978. It is a KEIHIN Japan, ser#28AD0E(best I can tell). Also has on the side either PB or P8. Anyways, some of my parts will fit and some not. I think I have enough actual fitting gaskets, etc that I can rebuild. This carb does not have the Black pull out knob for high altitude that i see in the manual plus a youtube video by Tepco rebuilding a 1979 CT90 carb shows it on there. Then, the slow jet does not screw in. No slot nor nut sides for a wrench. It had me puzzled so I just got some pliers and was able to turn it, then just pulled it right out. It is totally stopped up so I am soaking it in Berryman carb cleaner.
Can anyone tell me how to find out what year this is? Also, the float is plastic and it has some fuel in it. See pictures below, the right side shows fuel half way up. Do I need to get a new float? or some how drain it and plug the hole? Thanks for any help.

 

[joel1234567]

Pretty sure that year doesn't have high alt knob but I've mostly dealt with the earlier years.
I get all my carbs now from wincycles. If you want a direct replacement they're a great source. Or, if you want to stay original, you can buy the copied carb from them and swap over all the parts for probably the same price or less than a rebuild kit.
I know that doesn't directly answer your questions but it should get you new jets, knobs, float, etc that you need. I never have good luck with those rebuild kits.

I suppose if you needed to you could drill and drain the float and then epoxy over the hole but that seems like a lot of extra work.
Slow jet without slot seems unusual but again not sure if there's some idiosyncracy there to a later model CT90- but I don't even think I've seen one in any carb without a slot in it and screw in.
Make sure to clean out all the passages in the old carb as well if you reuse it, and blow them all out clean with compressed air. Depending on how gunked they are it can take a few passes.

 

[-Nate]

O.K., sorry for the late reply, I've been in Death valley awhile .

The 1978 & 1979 use the same carb, no high altitude valve, here's the link for parts : https://www.cmsnl.com/honda-ct90-trail-1979-z-usa_model7162/partslist/E++1401.html

See if I can post an image :

 

[-Nate]

List of parts and numbers, you'll need a new float, don't try to fix the old leaky one .

The press in idle jet is standard, it has an emulsion tube attached, clean it out well with fine wire .

1

GASKET SET​

product number: 16010096305


€ 15.00
(USD 16.31 ,incl. 0% VAT)
PACKING SET product number: 16010096721

supersession: 16010096305

(USD 16.31 ,incl. 0% VAT)

FLOAT SET​

product number: 16013883005
(USD 19.03 ,incl. 0% VAT)

CARBURETOR ASSY.​

product number: 16100102774
(USD 302.89 ,incl. 0% VAT)

CARBURETOR ASSY​

product number: 16100102775
(USD 302.89 ,incl. 0% VAT)

CAP,RUBBER​

product number: 16118121014
(USD 3.81 ,incl. 0% VAT)

VALVE,FLOAT​

product number: 16155883005
(USD 34.80 ,incl. 0% VAT)

HOLDER, NEEDLE JET​

product number: 16165102730

Hurry: only 1 left!

(USD 9.24 ,incl. 0% VAT)

SCREW,PAN,3X14​

product number: 93500030140H

supersession: 93500030141H

(USD 0.54 ,incl. 0% VAT)

SCREW,PAN,3X14​

product number: 93500030141H
(USD 0.54 ,incl. 0% VAT)

SCREW-WASHER,4X14​

product number: 938920401408
(USD 0.54 ,incl. 0% VAT)

WASHER,SPG.,3MM​

product number: 9411103800
(USD 0.54 ,incl. 0% VAT)

CLIP B7,TUBE​

product number: 9500202070 (USD 1.09 ,incl. 0% VAT)

JET,MAIN,#65​

product number: 991011160650
(USD 8.70 ,incl. 0% VAT)

MAIN JET KIT #58 #60 #62 #65 #67 #70(NON O.E. ALTERNATIVE)​

product number: 09910116000

alternative part
(USD 16.86 ,incl. 0% VAT)

---

---

 

[-Nate]

Whew ! I had to trim off a lot of that last image to make it post, you get the idea I hope .

Kester is the best non OEM but I prefer factory HONDA parts as most are still made in Japan and will outlast you .

 

[longbowelk]

Thanks for all the info. I did get the gasket kit and the carburetor kit from these people. I got a new float from another source off ebay. It fit fine.
I finally got it all put back together over the weekend. Now I am having trouble with what I believe may be the throttle cable. It may need some sort of lube or adjustment. The bike cranks and runs. However, when accelerating it sometimes sticks and keeps revved up. Other times it dies. I tried to get it going to ride and it got about 20 feet and quit. I think the needle jet is not responding well. Please refer to my youtube video and if any suggestions please advise.

Thanks, Alan

 

[joel1234567]

Few thoughts-

A new float is typically not just drop-in. The height needs some adjustment. You might get lucky, but if you didn't perform an adjustment that might be one thing to go back to.

The idle could be a few things, hard to tell from the video. Might be a slight air leak and hanging idle. Double check the air adjustment screw on the carb for adjustment. Make sure the O ring/gaskets/etc are on the carb and things are firmly bolted down. Not like crazy tight- too tight can warp it a bit. Set the flat surfaces on some glass, do you see any warps? Some people recommend spraying a little WD40 on the edges, listen for a change in idle, I've never had much luck with that. I typically just go back thru and make sure all gaskets are in place, things are tight, etc. Make sure throttle cable "entrance" (I dont know what its called... the place where the cable enters the carb) on the carb is screwed down tight, I think there is a thin little gasket in there too.

Pull off the throttle assembly, clean and lube it if you haven't already. It might be hanging up a bit. They get pretty gummed up.

Make sure that where the throttle cable enters the throttle assembly it is pushed all the way up in. Triple check it. It should fit very snugly into an opening up there in the handlebars, just before where the cable fits thru a little gap. Also make sure that the throttle cable housing itself is pushed up firmly as far as it can go up into the handlebars. Sometimes the cable housing pulls down a bit and effectively shortens up the length of cable you have at the carb end.

Maybe adjust the cable too where it enters into the carb to give it just a bit of slack. Definitely shouldn't be increasing idle when you turn the handlebars.

And sometimes you just keep monkeying with it enough times that it magically all starts working and you really have no idea exactly what you did to fix it.

 

[-Nate]

Hi Alan ;

Thanx for the good video; one problem is obvious to me, the throttle cable is mis - routed, it needs to go above the chrome engine guard down pipe ~ there's supposed to be a plastic cover that holds it in place from flopping around, just use an Adell clamp or similar and a 6MM fastener to hold it loosely in place .

Once the cable has been miss routed it often gets pinched in the steering stops, easy to test : remove the throttle cable from the bike and loop it in your hand no larger than a 4" loop, now see if the center still slides easily back and forth with ZERO DRAG - if any drag no matter how slight the cable is kaput , they're not expen$ive to buy, I recommend the correct Japanese made ones, easily available OnLine .

You bike looks great ! I see so many that are hammered nearly to scrap yet keep on running fine thanks to proper servicing .

Whatever you do, DO NOT EVER ride any Motocycle that has the engine speed up when you turn the handlebars ! I know this only has 9 horsepower but it can and wil bite you badly if it gets the chance .

Test / fix / replace that throttle cable first, it looks to me like you're really close to riding time .

BTW : ALL round bowl Honda 90 carbies have non adjustable plastic floats .

 

[longbowelk]

Hi Alan ;

Thanx for the good video; one problem is obvious to me, the throttle cable is mis - routed, it needs to go above the chrome engine guard down pipe ~ there's supposed to be a plastic cover that holds it in place from flopping around, just use an Adell clamp or similar and a 6MM fastener to hold it loosely in place .

Once the cable has been miss routed it often gets pinched in the steering stops, easy to test : remove the throttle cable from the bike and loop it in your hand no larger than a 4" loop, now see if the center still slides easily back and forth with ZERO DRAG - if any drag no matter how slight the cable is kaput , they're not expen$ive to buy, I recommend the correct Japanese made ones, easily available OnLine .

You bike looks great ! I see so many that are hammered nearly to scrap yet keep on running fine thanks to proper servicing .

Whatever you do, DO NOT EVER ride any Motocycle that has the engine speed up when you turn the handlebars ! I know this only has 9 horsepower but it can and wil bite you badly if it gets the chance .

Test / fix / replace that throttle cable first, it looks to me like you're really close to riding time .

BTW : ALL round bowl Honda 90 carbies have non adjustable plastic floats .

Thanks for the info. I was going to redo the video and leave out the steering issue since we had routed it wrong but I was wore out and it wouldn't crank. What source has the Japanese cable? I will review your notes on the cable and tackle it next. Thanks for all the help, Alan

What is best method to clean and lube?

 

[joel1234567]

Doh, thanks for the correction Nate on my miss on the carb float, didn't realize that the later plastic floats were not adjustable. Keeping the record straight 👍

 

[-Nate]

Okay, first you need to remove and test it .

I'm betting it's been pinched and so is ruined .

Here's where I I get many OEM Honda parts : https://www.cmsnl.com/honda-ct90-trail-1979-z-usa_model7162/partslist/F++02.html

The cable you need (1979 Model year) is : 17910102790 and for $26 I'd just by it having dealt too many times with off brand and Chinese made cables that don't quite fit .

However, you now have the part number so go search Amazon and E-Bay, I bet there will be a new old stock one somewhere out there for le$$ .

Once you remove and test it we can go from there .

I still have the 1978 CT90 I got for my then 13 year old son to ride to school ~ he was born in 1979 and I was looking for a '79 model but found this 800 mile CT90 clean as can be in a Dempster Dumpster after some old guy died and they threw out all of his tools and lawnmowers etc. .

 

[longbowelk]

Okay, first you need to remove and test it .

I'm betting it's been pinched and so is ruined .

Here's where I I get many OEM Honda parts : https://www.cmsnl.com/honda-ct90-trail-1979-z-usa_model7162/partslist/F++02.html

The cable you need (1979 Model year) is : 17910102790 and for $26 I'd just by it having dealt too many times with off brand and Chinese made cables that don't quite fit .

However, you now have the part number so go search Amazon and E-Bay, I bet there will be a new old stock one somewhere out there for le$$ .

Once you remove and test it we can go from there .

I still have the 1978 CT90 I got for my then 13 year old son to ride to school ~ he was born in 1979 and I was looking for a '79 model but found this 800 mile CT90 clean as can be in a Dempster Dumpster after some old guy died and they threw out all of his tools and lawnmowers etc. .

The cable is not available from CMSNL. My search on Amazon and ebay another zero. Looks like I'm having to decide which Chinese cable to buy. I have noticed the rubber cap on top of carb that cable runs through is cracked and loose. Not sure if that is a big deal but I may replace if I can find one. Also, there is not a rubber washer gasket in the top of the cap so another piece to find and put in.

 

[-Nate]

Okay, progress of a sort .

Did you remove and test it exactly as described ? .

Western Cycle used to sell Keyster kits and parts .

 

[longbowelk]

I have not tested it yet. I hope to be able to today or tomorrow. I am assuming the test would be to disconnect from the carb side, then roll it up into a 4" hoop and finally activate the throttle grip.