FZRSupport: the FZROnline Archive

My 98 is having major issues. First when I give it throttle it bogs. Give more forceful throttle and it runs . Soon as I get off the throttle it backfires. So besides the carbs not being tuned properly I think the spark plug threads on cylinders 2 and 4 are stripped. Reasoning is those plugs don't seem to tighten all the way down. 1 and 3 plugs go further down into the head. Bike starts and idles around 1000rpms once warm. Its just the bog and backfire that has me considering swapping out the head. I bought an engine off a 92. How difficult would it be to swap the heads? Or should i just take it to a shop and let a mechanic do the swap for me?

mark1914 wrote:My 98 is having major issues. First when I give it throttle it bogs. Give more forceful throttle and it runs . Soon as I get off the throttle it backfires. So besides the carbs not being tuned properly I think the spark plug threads on cylinders 2 and 4 are stripped. Reasoning is those plugs don't seem to tighten all the way down. 1 and 3 plugs go further down into the head. Bike starts and idles around 1000rpms once warm. Its just the bog and backfire that has me considering swapping out the head. I bought an engine off a 92. How difficult would it be to swap the heads? Or should i just take it to a shop and let a mechanic do the swap for me?

Mark1914,

How much wrench time have you put in on cars / bikes ? What do you have in the way proper tooling Torque wrenches / sockets etc.?

Geo, honestly little to no time wrenching. Its in my blood though if that counts. My grandad and dad restore old cars and sell them. I personally have always owned a car that didnt need anything but brakes and oil changes done it. This FZR has been my first real wrenching experience. Tools I have. Sockets, T-handle wrenches etc. No torque wrenches though.

If you already have a motor from another bike, pull the head off that motor so you can see how it comes apart and goes together, I just did mine for the same reason of damaged plug threads. It isn't bad just time consuming. You WILL want a torque wrench as torque specs a really low and very easy to over torque and break bolts. Biggest pain for me was getting it timed again, crank kept wanting to move but I did do mine in the bike. Get a manual and take your time. Ask your Dad for help if you need it.

tkclow wrote:If you already have a motor from another bike, pull the head off that motor so you can see how it comes apart and goes together, I just did mine for the same reason of damaged plug threads. It isn't bad just time consuming. You WILL want a torque wrench as torque specs a really low and very easy to over torque and break bolts. Biggest pain for me was getting it timed again, crank kept wanting to move but I did do mine in the bike. Get a manual and take your time. Ask your Dad for help if you need it.

Hi,
TKC has hit it right with that very sound advice, might feel funny about going to Dad but DO it , it takes an "eye" to look at valves and say whats what

be careful taking the head off your supposed to follow a criscross pattern so you dont warp it. (bolting it on and removing it)