Author Topic: cb 750 f2 brat - top end rebuild in progress.. (Read 18247 times)

thx for the comments guys!

and indeed, it's not the most comfortable of seats... with a regular jeans it feels like you're sitting on two pipes (which you actually do... :p ) but with my kevlar jeans with padding it's not that bad at all...

drove it to work today so did a far bit of highway (about 30 miles single way), and I noticed an oil leak. drops are coming from the oil lines but not were it's bolted to the engine... will have a closer look later on...

SOHC4 Cafe Racer Fan · « **Reply #57 on:** September 05, 2014, 09:30:51 AM »

Koen,

You've been nominated for Bike of the Month. Please go to the BOTM nomination thread and reply with an acceptance.

koendd · « **Reply #58 on:** September 11, 2014, 02:20:27 PM »

sweet, thx for the nomination!

but in the meanwhile some troubles... found a little puddle of oil under the bike...
The longer oil line had a hole in it...

went to a shop in about 30mins from where I live where they mounted a new braided hose for about 20dollar so that's cheap enough!
unfortunately one connection was leaking pretty bad so had drive all the way back to let them fix it.

got back home, mounted everything again just to see that the longest line is to long!

so tomorrow another hour in the car to shorten the line...

but to keep the mojo up did some electrical work (never thought I'd say that...)

as it was

as it is now

maybe you can't really tell but "deleted" the right steering switch. Moved the ignition on/killswitch to a flick switch on the headlight and found an unused button on the hi low beam switch to act as the starterbutton

also ordered a shorty megaphone as the exhaust is shooting when letting go off the throttle...

koendd · « **Reply #59 on:** January 17, 2015, 12:27:28 PM »

sooo, after a rather short riding season (about 1200km's) I decided I had to change the leaking pucks...
my jeans were full of oil all the time and smoking alot from the exhaust as well because of the oil dripping on the headers

so had a go at it.

found loads of things wrong with the cilinder head..
one of them was a loose bolt...

camshaftholder was loose

and there was a K head on my F cilinders/pistons = loads of compression (probably to much?)

result of a K head of F cylinders and F cam:

So now I'm really considering my options here...
The cilinders and pistons are good, and I bought an F2 head with good cam but possible worn guides.

Or: I have a good K head and pistons, So I could use the F2 cilinders, with K pistons and a K head.
That would leave me with an F bottom end and a complete K head (possibly with 836cc kit).

Really have a hard time deciding what to do... So please help me out here

Riceman · « **Reply #60 on:** January 17, 2015, 10:42:03 PM »

Just seen your build for the first time,bike looks great.
Soon as I saw the Jupiler beer I thought of that crazy
car guy Mastermilo ...anyhow I'm sure you'll figure out
the head problem soon.

Davidov · « **Reply #61 on:** January 18, 2015, 08:18:40 AM »

You can repair that loose bolt with a heli coil...most likely. My F rebuild required a few thread repairs.

There are many ways to combine K and F engine components.

Personally I would build the engine with all matching parts, or some ugly problems may arise down the road.

koendd · « **Reply #62 on:** January 19, 2015, 04:03:59 AM »

Quote from: Davidov on January 18, 2015, 08:18:40 AM

You can repair that loose bolt with a heli coil...most likely. My F rebuild required a few thread repairs.

There are many ways to combine K and F engine components.

Personally I would build the engine with all matching parts, or some ugly problems may arise down the road.

yep I know, but that loose bolt was in the K head

allready sourced a good F2 head with no helicoils needed.

but read brandEn thread alot and saw advice from him to convert to K cilinders/head so that's why I'm in doubt again now..

koendd · « **Reply #63 on:** January 23, 2015, 12:43:05 PM »

well, bit the bullet and gave the barrels and head to the local machine shop.
They will check if honing is necessary and they'll deck the barrels and head, check the valves guides en replace if needed and build the head back up (valves)

in the meantime took some time to follow up on some threads on this awesome board and did some updates to my engine.

drilled the clutch basket with some extra holes

oilpump out, and installed the oil stopper kit I ordered:

no to bad to install, just messy to fill the oilpump back up

also replaced the small O-ring right here, but wen doing that (don't ask me why) I turned the wheel on the left (the one with the gap in it). But now I can't get it to turn back so I can reassemble. Any idea how I can turn in back?

as a last go the cilinder studs out. What a job

two of them snapped, and had to weld a nut on them in the end, got them off with the impact wrench.
others were with double nut and the help of a pipe wrench at the bottom.

thx for the help!

koendd · « **Reply #64 on:** February 09, 2015, 11:27:14 AM »

made some time for the F2 (since most of my time is going to the K2 now...)

got the engine out again to paint it good this time. the paint I used last year wasn't really fuel proof. it's okay on steel but turns out not on alu...
Will be easier to install HD studs this way to

since the engine was out decided to do some work on the frame. Some unused brackets were bothering me.

Since I'm using a rear F1 master cylinder the bracket for the brake fluid reservoir was just sitting there unused, same for the center stand brackets. So went ahead with the angle grinder, and touched the paint up with a spray can (the advantage of not powder coating a frame that is

)

koendd · « **Reply #65 on:** February 09, 2015, 01:18:12 PM »

since I was checking the oil while changing it on my K2 I took the oilfilter of my F2 as well,

this is what i found:

should I be worried now?

The head and cylinders are of the be rebuild at the moment but I'm worried something could be wrong in the lower cases...

Trad · « **Reply #66 on:** February 09, 2015, 03:39:47 PM »

Get a magnet and see if those particles are magnetic. That will help point you in the right direction.

Trad · « **Reply #67 on:** February 10, 2015, 10:15:45 AM »

I didn't notice the photo of your shredded cam holder. If those bit's aren't ferrous I'd guess they are from that. Are you planning on dropping the pan?

koendd · « **Reply #68 on:** February 10, 2015, 12:08:39 PM »

well, checked with a magnet, few bits were catched but 95% of it is aluminum luckily.

So my guess is indeed they are coming from the K head and the worn holders.

dropped the pan indeed, nothing to alarming there.

pieces you see in the pictures were mostly gasket

another question, is a stock F2 camchain in one piece? Because the one that's in it now has a split link in it.
no much sideways play either. only the tensioner will have to be changed the wheels already have some bits missing.

koendd · « **Reply #69 on:** May 29, 2015, 01:14:15 PM »

so, finaly got some funds to rebuild the engine.

Head and cylinders are with the engine builder. Bore out to 1.5+ oversize with new pistons + decking.
Installed new bronze valve guides in the F2 head I bought + valve grinding/lapping and decking the head!

some parts ready for glass bead blasting

painted the crankcase with high temp primer follow by satin black engine enamel

new oversize F2 pistons

installed new APE HD studs

finshed glass beading and painted with enamel

all new cam chain roller etc

oem F2 gasket

new pucks

installed a spare set of barrels and head to cure the HD studs (see brandEn's leak free topic)

and the bike waiting for its new heart...

bytio · « **Reply #70 on:** May 29, 2015, 01:32:51 PM »

The head on that engine is not F2, are you going to use an f2 head as those Pistons are to be used on F2 head the combustion chambers are larger on. The 410 head

bytio · « **Reply #71 on:** May 29, 2015, 01:33:55 PM »

Sorry forgot to add the head gasket is for a K model, (correct for the head on the engine in the pic)

koendd · « **Reply #72 on:** May 29, 2015, 02:23:01 PM »

the head in the pictures is just to set the Ape studs. will not be used on this engine.
The F2 head is still with the engine builder.

will check the head gasket.. thx for the info!

bytio · « **Reply #73 on:** May 29, 2015, 02:23:47 PM »

Sent you a PM with gasket details

koendd · « **Reply #74 on:** June 02, 2015, 01:29:50 PM »

mailed the supplier, they will send me the correct F2 gasket! thx for the info!!

finally got my cylinders and head back from the machine shop.
Painted them ASAP

decked and new bronze valve guides installed + valves lapped

bored to 1.5mm oversize

matching F2 pistons 1.5mm

since I didn't want to sleep on the couch (or garage...) decided not to put the parts in the kitchen over so made one out of a cardboard box with expensive tape on it

new pistons and camchain parts in place

hope to get it back together by the end of the week, but still waiting on some parts though...

thx for watching and please do say so when I'm about to mess up

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Author Topic: cb 750 f2 brat - top end rebuild in progress.. (Read 18247 times)