1988 kat HELP!!! timing issue

[1988katanabasketcase]

Hello, i had more or less a 1988 katana 600 basket case. The bike only has 4k miles on it, but it has sat since 1989 because PO took a nice fall. I put new plugs in, cleaned the carbs, new fuel lines, cleaned the gas tank and finally got it able to run. BUT the issue is when sitting with the choke off after warming up rpms bounce back and fourth from 1 and 2 ??? also when you rev it up, it dies when the rpms come back down. Also when i took it for a ride and i was in first gear sitting at idk maybe 4k rpms it would grab and i would start to accelerate then it would kinda skip and then grab again.


IS this a timing issue? valves? timing chain ?

Someone please help and tell me what kind of repair I'm looking at and expenses.

[maniac1886]

sounds like a vacuum leak to me. all that old rubber sitting, rotting away
get it running n.spray carb.cleaner around the intake boots between the carbs n head, n carb boots at the airbox. also any vacuum lines. when u fine the vacuum leak it will suck up the carb.cleaner and ur rpm will increase.

[Kreylyn]

Hello, i had more or less a 1988 katana 600 basket case. The bike only has 4k miles on it, but it has sat since 1989 because PO took a nice fall. I put new plugs in, cleaned the carbs, new fuel lines, cleaned the gas tank and finally got it able to run. BUT the issue is when sitting with the choke off after warming up rpms bounce back and fourth from 1 and 2 ??? also when you rev it up, it dies when the rpms come back down. Also when i took it for a ride and i was in first gear sitting at idk maybe 4k rpms it would grab and i would start to accelerate then it would kinda skip and then grab again.


IS this a timing issue? valves? timing chain ?

Someone please help and tell me what kind of repair I'm looking at and expenses.

Well, your looking at a situation where multiple things are causing problems, but none of it "hard parts".


Rubber dries out, especially when not in use. Your bike has rubber in the carbs, attaching the carbs to the airbox, to the engine, capping off vacuum ports and rubber vacuum lines, so on... And by now they are old, hard, and not sealing right.


I would expect that you need to rebuild the carbs, reseal the boots on the airbox, replace the o-rings on the engine boots, replace vacuum and fuel lines, check the petcock internal diaphragm and O-rings are working, and flush/change the oil, check the plug wires and plug boots, clean/check all electrical connections.


You mentioned some work already. Did that include replacing any cracked or worn parts in the carbs and surrounding parts attached? Have you done a vacuum leak test when the bike is running? Have you confirmed the fuel flow is correct?


Things I would have no reason to believe are part of the issue... transmission, engine internals (cases maybe because of the fall, but that oil leak should be obvious. ) and so on.


Costs are... well, dependent on who's doing the work. I would expect that I would spend around $50 for all that IF the major boots and such were useable. If an OEM shop was doing the work, the bill would be upwards of $1k. Engine boots new are upwards of $35 a pop now days, so if those are bad... that adds up quick.


Krey

[1988katanabasketcase]

also forgot to include that there is a weird ticking noise that comes from around where the headers connect to the motor at first i thought the bolts were loose but tightened all them so obv not that....and there are no vacuum leaks all rubber is intack

[1988katanabasketcase]

1988 kat HELP!!! timing issue

Hello, i had more or less a 1988 katana 600 basket case. The bike only has 4k miles on it, but it has sat since 1989 because PO took a nice fall. I put new plugs in, cleaned the carbs, new fuel lines, cleaned the gas tank and finally got it able to run. BUT the issue is when sitting with the choke off after warming up rpms bounce back and fourth from 1 and 2 ??? also when you rev it up, it dies when the rpms come back down. Also when i took it for a ride and i was in first gear sitting at idk maybe 4k rpms it would grab and i would start to accelerate then it would kinda skip and then grab again.

also forgot to include that there is a weird ticking noise that comes from around where the headers connect to the motor at first i thought the bolts were loose but tightened all them so obv not that....and there are no vacuum leaks all rubber is intack

IS this a timing issue? valves? timing chain ?

[mammut89]

I still vote for vacume leak. try spraying some starter gas around the carb intake boots etc..

[Kreylyn]

also forgot to include that there is a weird ticking noise that comes from around where the headers connect to the motor at first i thought the bolts were loose but tightened all them so obv not that....and there are no vacuum leaks all rubber is intack

Damaged header gaskets from falling over would not be something you can determine with out removing the header, and they could cause a leak yet still be tight.


stick to one thread please.


Krey

[lastleg]

i vote airbox.... it's a finicky thing.

[maniac1886]

the fact that the needle bounces at idle is a tell tale sign on a vacuum leak
sometimes the aitbox boots pop off when trying to put them on the carbs. I took my airbox off and glued them to it to mitigate that.

as for the ticking, I vote exhaust leak

[1988katanabasketcase]

alright well if everyones voting a leak must be a leak. Thanks everyone and sorry krey was just trying to get more opinions on my problem.

but the best way to find the leak is to spray fluid? ( what kind of fluid ? ) around all my rubber boots ?

[maniac1886]

You use carb cleaner/starting fluid because if there are any little cracks in the rubber where air can be sucked through, it will pull that spray into the ignition system and increase idle. The rubber may look all in tact to the naked eye but you would be surprised what you find

So if you look at your carbs, in front of them there are four rubber boots that connect the carbs to the motor. And behind the carbs there are four rubber boots that connect the airbox. You want to spray Carb Cleaner or Starting Fluid at each one of those while the bike is running.

Do it one at a time, be careful not to fill the whole area with haze because then you wont know which ones. Spray the boots one at a time and wait for the idle to jump.

After that, there are four nipples that stick up on the top of the carbs one on each carb, you will see them sticking up off the black caps on the carbs. They all should be capped off. Spray starting fluid around those caps. (may be better off just replacing them).

There is also a vacuum hose that goes from the Right side carb (if your sitting on the bike) up and over the carbs to the petcock on the gas tank. Spray that too.

There is a breather hose that connects the airbox (top center) to the motor. Spray that.

Also check the bottom of your airbox, there should be a drain hose on the bottom center. That drain hose should be capped off. If not, cap it. My bike didnt have a hose when i got it so I just capped the nipple the hose would clamp to.

When putting the airbox on the carbs, the airbox boots have a tendancy to pop into the airbox and lose their seal. Be careful that you dont do that when installing the airbox. Like I said, I glued my airbox boots to the airbox to ensure a solid seal as well as mitigate them popping off everytime I put them on the carbs.

The intake boots (between the carbs and engine) have gaskets in them on the engine side. I had to replace mine when I had my vacuum fiasco.


Once you get the vacuum issue sorted out, you will... I repeat YOU WILL have to clean your carbs. Take a look at carbs 101 on this forum. Lots of pictures, step by step instructions. Follow them to a T. Yes it requires patience but it will be worth it in the end.

Once you get your carbs cleaned you will need to Sync them. There are tools for syncing carbs. Easy peasy. Just youtube it, or search it here.