US import GPZ1100 maintained by cowboys

[JimBoUK]

Today I started dismantling the engine of my new GPZ1100 project.
The first thing I noticed is one of the rocker cover bolts was missing.
Fortunately the cam lobe and bearing surfaces look good and also the half shell bearings
There are however problems with the bolts for the camshaft caps.

One camshaft cap has a bolt missing and another bolt is replaced with an oversized stud and nut where the thread was obviously knackered.
Another cap also had an oversized stud and nut.
Another cap had 2 oversized bolts
Where the bolt was missing the remains of a bolt is left deep in the hole after removing the cap and it looks like someone has tried to dig it out !

I think I need to get an expert to remove the sheared bolt then check and repair all the threaded holes in the head. I assume the preferred approach here is time-sert's, not heli-coils ?
I was going to do the work on the head myself e.g. take out valves, check guides, check seats, re-grind valves etc. If it does need new guides or seats I've never done this. Not sure if it's something to fairly easily do yourself ?

My options are:
1. Rebuild head myself and get engineering company so sort threads
2. Get reputable company to do all the work on the head

Any idea of ball-park costs of either of these options and who to use (ideally in or near Bedfordshire)

[chrisNI]

Buzzard is the man to speak to about heads

[Al]

That does not look too terrible at least not when compared to some. Threads can be repaired, bolts replaced, broken stuff removed. It needs to be done by someone who is familiar with the possible complications of conducting work at this level. If you pull the buckets out you need to satisfy yourself that what had been done so far has not compromised the wells that they sit in. Its possible to collapse the walls inwards by using oversize studs / bolts or fixings of a greater length than standard. There are a number of first rate engineers on here who are capable of retreiving the situation. Personally i would not get involved myself but entrust it to someone who knows what to do.
AL

[8 Valve Mark]

i totally agree with both Chris and Al, speak to dave (buzzard) alternatively i know of 2 NOS b1 heads recently offered to me, either of which might surprisingly be a cheaper alternative. i have a full airbox n metering gubbins too minus the 4 injectors (the easy bits) if reverting to injection is an option jimbo.pm if your interested. cheers m

[Philippe]

Hi JimBoUK
take a look at this:
https://z-fever.de/shop/de/product_info ... pf-b1.html
I have no idea about the condition of the head but for 75 Euro I think it's worth the while...if you want to go back to original.
Andre, the shop owner, understands English.
Your cylinderhead can be rescued but it will cost more than 75 Euro I 'm afraid.
Just a tip to avoid damage to the threads: maximum torcque for the cap bolts: 1,2 Kg/m not 1,7 as indicated in the workshop manual!
And when rebolting the caps: hold the camshaft down by hand in order to minimalise the stress on the thread until the bolt is deep enough in the head.
GrtZ
Philippe

[zed1015]

Easy fix for any competent mechanic or machinist..
Oversize holes can be rescued with a custom threaded insert if they are oversize for a common insert and the broken bolt will succumb to a cobalt drill.

[Simonic]

I once bought an 1100R from Cusworths in Doncaster..... The cam caps were held on by UNC thread slot screws for some reason....
B340GWF Where are you now ?

[zed1015]

I once bought an 1100R from Cusworths in Doncaster..... The cam caps were held on by UNC thread slot screws for some reason....
B340GWF Where are you now ?

That was Cusworths for you..
My mate took his tuned CB900FA in for a service and it came out running a bit milder.
Turned out one of the mechs had the same bike and "somehow" the cams got swapped.