Just bought a KZ305 and I need help with two thing

I bought a 1987 KZ305 with 15k on it the other day and got a good deal on it. It runs great, fires up on the first try, etc...

However, the bad is a small oil leak towards the front / front left side of the engine. It's not pouring out oil, but I would probably need to add oil weekly to keep riding it.

The only other problem with the bike is that at high rpms, sometimes the gears slip, at above 7k rpms, it might slip, but never below that. It doesn't always slip, just sometimes. Also, when I am changing gears, if I try to shift to quickly, it might slip. Is this a clutch problem?

I think that the oil leaks is from a bad valve cover gasket, if this is what you guys think too, could someone please point me to a tutorial for changing one out?.


I am going to try to do all work by myself, at least on the valve cover gasket.

Any help would be greatly appreciated, thanks!

welcome, and it sounds like a clutch issue, I would recomend doing a search here to see if a FSM has been added to the site, but a valve cover is a simple process.
One thought on the clutch slipping, and I dont know the bike very well, maybe someone has changed the oil and used modern car oil,it has additives that can cause a wet clutch to slip

I'm planning on changing the oil today... So hopefully it will solve the clutch issue... I sure hope so.

Ill try to find an FSM

Thanks!

I would do a clutch adjustment as per the factory manual. Sometimes the Clymer manual is ambiguous as to which way you're supposed to turn the adjusting screw. As for the oil, Shell Rotell-T, Chevron Delo & Valvoline Premium Blue would be good to use & they're usually cheaper than other oils. 15w-40 is usually what the auto parts stores have & their ZDDP content is about the same as motorcycle oils & racing oils.

Thank you everyone for the help so far.

I changed the oil last night, put castrol 10w-40 in it (all my auto store had)and rode it to work this morning.

I figured that it will leak about a half a quart every 100 miles or so. It is a pretty severe leak from what I can tell.

About how much is a valve cover gasket....if yall think that this is the problem.

I looked at the engine today after riding, I can see a leak around the top / front side of the engine.

Z1Enterprises.com might have the gasket - it probabaly doesn't cost too much. You kinda have to be careful about what oil to use nowadays, since the amount of zinc dialkyldithiophosphate (ZDDP) in regualr motor oils has been reduced significantly in recent years. Check the MSDS to see what the content is: somewhere in the 1.5-2.0% range is typical for heavy duty diesel engine oils, motorcycle oils & racing oils. The phosphorous in ZDDP is a sort of last line of defence against metal-to-metal wear.

I got Castrol 4 stroke 10w-40 motorcycle oil, but I will definitely check for the MSDS info, as I'd hate to do some damage to the engine.

Also, I can't find a service manual for the bike...

Does anyone know where I can look at a copy of it? I found one to buy for $51.50, but thats a lot of money for a manual.

Any ideas?

I just checked z1enterprises and they don't have a valve cover gasket for my year bike from what I could find. Any other ideas of where I can find one? I've tried doing a google search, but no luck.

Thank you

Motorcycle oil will be fine; I'd guess that all of them have a good amount of ZDDP.

Z1 doesn't list everything. If you can't find something, call or email them.

Search ebbaayy for KZ305 manual... maybe there's one listed.
The back outer cover of the factory manual will list the models covered.

Does anyone know the part # for the valve cover gasket? I'm on cheapcycleparts.com and they have diagrams, but I don't know what to look for other than the name valve cover gasket...

I did email z1 btw. Just waiting on a response.

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As I recall, the 305 motor is a singe overhead cam setup. I havn't tuned on up in 20 years so I can't recall all the details.

Regardless, if it's rocker arm adjusters, there will be 4 caps with O rings on top of the motor. They mount into the rover cover. If the rocker cover is leaking, thay may or may not take a gasket. Sometimes they just call for case sealer on rocker covers.

Check one of the OEM Parts sites with on fiche...

Great littl bikes BTW. Get those couple problems sorted and you'll like that bike

Larry C

I've been riding it in to work this week a few times and my initial guess was wrong. It's not leaking a half a quart every hundred miles, but under a quarter of a quart if not less..

It's not that big of a deal and I'll just keep riding and adding oil until I can figure out the problem.

As far as the gears slipping, it ALWAYS slips at 6k rpms... then if I let off the throttle, and then rethrottle, it always catches and holds.. I'm not sure what it could be, but I need to figure out where a manual is so that I can adjust the clutch and see if that helps.

Thanks for all the help so far!