'91 Jet kit & exhaust?

Discussion in 'Mechanics Garage' started by Hero Danny, Aug 20, 2016.

  1. Hero Danny

    Hero Danny New Member

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    Hey everyone! Well I decided that if I am going to take apart these complicated carbs and start doing some intensive cleaning.. thought I mine as well do some upgrades..

    First off, exhaust... I looked at the mid pipe and holy, cow. So many cats and emissions stuff. I want to rip it all out.. I'm thinking about replacing it all with aftermarket headers to clean it all up down there. Any suggestions on which one I should get?

    Another thing about the exhaust, I'm considering maybe doing a left exit exhaust... or a shorty exhaust. I want to see that swing arm. Any suggestions?

    And finally, the carbs... if I'm going to do a full system, then I will need to rejet. Currently it has a yoshi slip on. I wasn't sure what jet sizes are recommended? Or any jet stage kits, etc.? I'm going to be cleaning the carbs sometime this week so I think I will just order the jets. Any idea on what jets I would need for just a slip on, and what jets I would need for a full system?

    Thanks for any info!
     
  2. ridervfr

    ridervfr Member

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    I have the same slip on and went with stock jets etc. You should get a factory service manual, all the jet sizes etc are listed along with plugs, very informative. Left exit exhausts are rare as hens teeth. If you find one, you wont be able to use a service stand on the hub without removing the muffler, not a big deal but I use mine every time I grease my chain. I do remove the muffler to take the rear wheel off though. My other bike, the 91 has shimmed needles and I really dont notice much of a difference, there are already shims there anyway, I added .020 You can remove that PAIR crap with some block off plates on your cylinders and capping off some stuff on the air box along with a few things on your plenums. I cut off the pipes and welded up the holes.

    If your having issues with starting and some low speed rideability, you can remove the fuel mixture screws, (you know the "things" that are supposed to be 2.5 turns out) and blast some carb cleaner in there followed by some air (if you have a compressor.) Poor mans carb service. Love the sound of the Yoshimura slip on by the way. V&H slip on sounds pedestrian, remember not to use the word "Fuck" so much, as there can be cun*t around :pound: :pound: :pound:
     
  3. Hero Danny

    Hero Danny New Member

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    Working on getting one from ebay right now.

    I didn't even think of that!! Oh well, I think I'll forget that plan then and just go for a shorty exhaust if I can find one!

    Sorry, I'm bad with the terminology, what's "PAIR" mean? Also is there any write ups or anything on how to do this? I may just buy a full system.


    Good idea! I'm going to follow that intensive carb guide and see if I can get everything up to 100%
     
  4. Hero Danny

    Hero Danny New Member

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    Okay, so I've decided to just stick with my OEM Jets. I started tearing apart the bike. Seat, plastics, tank, then finally the fun part..

    Holy hell, I was completely taken back when I lifted that gas tank and it revealed to me the air box and carbs. That immediate feeling of being overwhelmed the second I laid my eyes on everything. Hoses all over the place, wires, tight spots, metal, grease, dirt. Wow, I just didn't even know where to begin... Quite a bit different from my old KLR 250! That's for sure!


    Where do I begin? Well, let's start with the air box. Holy hell, the air filter had seen better days! It's a uni filter, and most of the spongey material has deteriorated away... Note to self, never buy another uni filter... wow... I guess they work for dirt bikes okay, but no thanks for any street bikes. I am going to be throwing this one out. I already ordered a new Hiflofiltro air filter.

    pics.jpg

    So after messing with the air box, finding out that there is a gasket on it (which hopefully can be recovered with some gasket sealer) I finally make way to the carbs. Again, feeling incredibly overwhelmed I began to think about my attack approach. I decided I would start with the easy (or so I thought) I tried disconnecting some of the old hoses.. HOLY CRAP! I never had this much trouble taking a simply hose off! There were like welded onto the ends. Luckily with some persuasion of a screw drive (gently of course!), some power blaster, and the twisting motion, I was able to finally release the hoses. I then began on throttle cables, and choke cable. Until finally realizing just what a nightmare those little clamps were on the rubber boots. They were so hard to access from the right side. I spent about 30 minutes trying to just get those two undone! Crazy... Anyway, got those undone and used a pry bar to lift the carbs off the engine. I immediately stuffed the engine with some rags to prevent any "woopsies". And at last had that carb off!

    IMG_2118.jpg

    I also noticed that my secondary air filter? Whatever that thing is called. In that small little box, it was all deteriorated as well.. I ordered a new one of those too..

    I cleaned out all the jets and float bowls, took out the jets ran a pin through all the holes, then sprayed carb cleaning through them. Then I went ahead and sprayed some down into the holes that the jets seat into as well. I think I got all that fairly clean, I don't want to go crazy with the carb cleaning. It doesn't have to be perfect. I just want it decent. In my experience once you start taking out gaskets and float valves, etc. that's when things start to F up.

    I did every carb, I wanted to know if there are any other steps you can recommend that are relatively easy. I have the carb off now so I mine as well do it. I still have to clean out the fuel mixture screws. Should I leave those at 2.5 turns? Or is it recommended that I richen up the mix a tiny bit?
     
  5. kennybobby

    kennybobby New Member

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    Were the carbs clogged up? If so then you need to pull the pilot jets to clean the cross-drilled holes in the emulsion tubes, same for the main jets. Most carb cleaner sprays don't do squat for cleaning out the tiny pilot jets.

    And it does matter--there is no just getting it close, everything does have to be perfectly clean and fully open to the correct diameter or it won't run. But don't take my word for it-- just ask the guys that have cleaned them 2,3,4, or 5 times and their bike still wouldn't run...
     
  6. ridervfr

    ridervfr Member

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    Can you take another picture of the carburetors - The reverse side - Did you remove the velocity stack plate? You know the thing that you see when you take the lid of the air box off.
     
    Last edited: Aug 21, 2016
  7. Hero Danny

    Hero Danny New Member

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    No, the carbs looked pretty clean actually. Also I did pull the jets out, I took each one out completely and poked a needle through each hole then I sprayed carb cleaner in them and then I sprayed more down in the hole, then I reinstalled the jet. I did this for both the main and pilot. Plus I cleaned the float bowls.
     
  8. Hero Danny

    Hero Danny New Member

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    I tried removing it but it seemed to be on there really tight. so I left it on. Should I remove it? Those screws seemed really tight.
     
  9. kennybobby

    kennybobby New Member

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    That plenum plate is DNR--Do Not Remove. Usually the screw heads are covered with a metal tab, just to slow you down and think whether you really want to take that off. Do not Remove the Plenum Plate.
     
  10. Hero Danny

    Hero Danny New Member

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    I was wondering about that, gotcha, I will NOT remove that lol. I'm just curious why I would want to remove the velocity stacks? I don't think I can remove them without removing the Plenum plate.
     
  11. ridervfr

    ridervfr Member

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    Glad you didn't remove them! Picture you took looked like you could have, its a DNR, unless you wana create vacuum leaks and broken t fittings
     
  12. Hero Danny

    Hero Danny New Member

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    Good thing those screws were so tight! I was trying really hard to take it off, haha, but gave up before I snapped a screw head. Good ol' honda looking out!

    Another little update, My oil filter arrived today! So I changed the oil and everything and it went actually really smoothly, surprisingly. Put in some good Rotella T6 and a K&N filter, old oil was fairly clean. Happy surprise because I also decided to pull the two rear spark plugs and take a look...

    Well, the plugs were in fairly bad shape, the one on the clutch side was really tight coming out (thank god it isn't cross threaded) and the one on the brake side was really loose (probably causing some blow by). They looked old too, I didn't take a picture yet, but I can tomorrow if I remember. Glad I ordered some AutoLite Iridium plugs to go in there! I'm definitely looking forward to replacing the filters, plugs, and finish the carbs. I bet the bike will really rip after that! :)

    I'm still looking for a decat exhaust or replacement headers. I saw some hi-mount slip ons on ebay for about $180 shipped. I am heavily considering it.

    I'm also going to do a compression test while i have the plugs out, just make sure everything is 100% before I invest any money into it.
     
  13. RVFR

    RVFR Member

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    Excuse me here, but take another look at the exhaust header. unless it's a CA model, and even then pretty sure 91s don't have cats my 96 didn't, nor the 98, didn't see em till 00. I'm not saying don't look for a header, just saying
     
  14. Hero Danny

    Hero Danny New Member

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    You're right. I guess it's called a "collector box", is what I'm seeing... huh, all I know is it's heavy and ugly! lol
     
  15. Hero Danny

    Hero Danny New Member

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    I just did a compression test and my bike is pushing 150 psi (to the back two cylinders) and that's with the bike is cold (haven't ran it in almost a week) and with 47,000 miles. I'm going to register the bike tomorrow, replace the spark plugs and do the final two compression tests.
     
  16. CandyRedRC46

    CandyRedRC46 Member

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    How much psi on the front two cylinders?
     
  17. Hero Danny

    Hero Danny New Member

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    I haven't checked yet... the radiator was a bit of a pain, i'll check before I put the new plugs in.
     
  18. ridervfr

    ridervfr Member

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    One bolt and the radiator moves out of the way, just bungee it to the fender on a towel. Let us know about the front two cylinders.
     
  19. Hero Danny

    Hero Danny New Member

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    Front two cylinders were the same, 150 psi. Bike is tight!

    Everything is all hooked up and it runs great! I had to replace the gas line today, cause that was old and leaking. She runs great though! I'm gonna take her to work tomorrow (kinda nervous!).
     
  20. ridervfr

    ridervfr Member

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    Pictures or it didnt happen :wink:
     
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