Author Topic: Blackfin CB750 F1 BLASTER (Read 28030 times)

Blackfin5 · « **on:** November 22, 2013, 03:03:04 PM »

It’s raining; it’s a Friday; and I’m sitting at the computer bored out of my mind, so I thought it would be a good time to start my F1 build thread. Like the title says, I want a BLASTER. This bike and the 550s will never see urban traffic - only open back country roads and some track days. I described the area in my other thread. On weekends there are more bikes on these roads than there are cars. Blast’n with buddies or blast’n for bragging rights - or blast'n solo.

The bikes have not arrived yet and will not until Thanksgiving weekend. Two ‘78 550s are coming from the East Coast and the 1976 F1 is coming from Indy. Admittedly, it’s an eBay purchase, but after being inspired by Tweakin’s and BrandEn’s builds, I couldn’t resist an impulse buy. I never thought FunJimmy’s build could be equaled until I read all of Tweakin’s pages (equalled - not necessary exceeded). Tweakin, remember, imitation is the best form of flattery. Thanks for sharing your build - I know it will be a good source of guidance for me. BTW, my shipping guy, Orlando, is great. $500 to $550 coast-to-coast in a covered rig; full insurance; polite; responsive; a man of his word. If anyone needs a shipper, PM me.

The F1 will be built in 2 phases. Please don't take this the wrong way - this bike will be a no expense spared build. The first phase will be basically everything (and new swing arm) except frame and engine until after my 550 build is completed, so I can get it on the road in short order. I may initially install a Gordon frame kit and a moderate cam and some head work, but only if needed. I want to ride it as soon as possible. Will keep the original tank - and I have a definite paint scheme in my head. I will also keep the stock front end, except add a 2nd disc up front. Second phase will be frame and engine. The frame will not be chopped, but perhaps some gussets added. On the engine, I really like what I see and hear with the 915cc kit, but may instead seriously consider MRieck’s billet block with 70cc pistons. Now that would be a Blaster.

Before any of the members post “keep it stock,” please know that every stock piece that comes off the bike will be boxed and stored for anyone in the future wanting to convert it back to original. So I do not really want to give away or sell any of the parts.

Although not yet arrived, here’s what’s already on the way:

Excel polished rims in WM4 and WM5.
BT-45Vs (110/90-18 & 130/80-18)
Motogpwerks 4-2-1 stainless exhaust
AirTech tail & seat base
RaceTech springs and emulators.
Bitwell clubman bars (no rear sets in first phase; but I’m very comfortable with stock sets).
Appliques for faded clock faces

Here's the '76 F1 in the PO's garage.

The 4-2-1 photo is compliments of Chris. I love the smooth bends and how this exhaust will give access to the oil filter. Hope there are zero fitment issues.

Thanks for reading.

tweakin · « **Reply #1 on:** November 22, 2013, 04:22:51 PM »

Man thats a nice starter bike Kevin! Looking forward to seeing what it becomes.

Blackfin5 · « **Reply #2 on:** November 22, 2013, 04:30:28 PM »

Thanks! Me too. Hope the frame is straight when it arrives.

SOHC4 Cafe Racer Fan · « **Reply #3 on:** November 22, 2013, 11:02:14 PM »

Quote from: Blackfin5 on November 22, 2013, 04:30:28 PM

Thanks! Me too. Hope the frame is straight when it arrives.

Why wouldn't it be straight? Any crashes in its history?

Blackfin5 · « **Reply #4 on:** November 22, 2013, 11:25:36 PM »

Not that I'm aware and the F certainly seems to be in very nice condition. Keeping my fingers crossed. Just saying frame because that would be the thing I'm least prepared to deal with. A cracked case 2nd. There's always a surprise when a bike isn't inspected personally. Now I hope I haven't jinxed it.

mitchie · « **Reply #5 on:** November 23, 2013, 06:25:26 AM »

That 4 into 1 is beautiful.

Blackfin5 · « **Reply #6 on:** November 23, 2013, 08:03:55 AM »

Here's another of the F1 engine. Air box looks great.

One more of the 4-2-1 - Chris' photos. I will need to fab an alum hanger to the upper shock mount. I really wanted a 4-2-1 and was about to pull the trigger on one at Cycle X. I'm sure that is a great exhaust but went for Chris' instead. The bike's original will be safely wrapped and stored.

I tried to purchase one of the exhausts for the Gulfstream 550 build, but he doesn't expect to be making any more til at least February.

mitchie · « **Reply #7 on:** November 23, 2013, 08:06:39 AM »

I'm in love with that exhaust.

Blackfin5 · « **Reply #8 on:** November 23, 2013, 08:17:01 AM »

Don't want to start a debate, but quieter than his 4-1 and "supposedly" for midrange, a bit more efficient that the 4-1.

Here's a photo of it installed on Chris' or one of his customer's bikes.

mitchie · « **Reply #9 on:** November 23, 2013, 08:53:57 AM »

I wish I had the scratch!!!! It looks very works.

CB750R · « **Reply #10 on:** November 23, 2013, 12:01:43 PM »

Great start plan on keepi g an eye on this one!

Blackfin5 · « **Reply #11 on:** December 23, 2013, 04:08:28 PM »

New bikes finally arrived. My "Blaster to be" 750 and two new 550s. One of the 550s has a true 9K on the speedo. The 750 and the 4-pipe 550 fired right up and run great. The other 550 could not maintain an idle and was sputtering and cutting out. I drained the little fuel left in the tank and ran some high octane. After a couple minutes it too ran well, but a bit of valve noise. Going to ride the 750 for a week or so before starting on the bike. Weather's fantastic, so just plan to enjoy it for a few days.

Merry Christmas.

Like this 550.

Shop building is getting a bit crowded.

Blackfin5 · « **Reply #12 on:** December 31, 2013, 05:12:57 AM »

Not much too report. My 550 build is stalled out with my frame waiting to be finished at Rob North's and the powder coater sitting on my cases. If I don't get them completed by the end of this week I will go insane. In the meantime, I been test riding the F1. 13,000 miles and it runs very well. Just a tad valvey until the engine warms up after about 45 seconds and some cam chain harmonic rattle at low RPMs. So being frustrated with the 550, I stated the F1 teardown. New rearsets, bars, control levers and trun signals on the way. Yesterday I brought the tank (no rust inside - quite surprised) and seat to the painter. I tried to purchase new alloy rims. I want a WM4 front and WM5 rear (both in 18"), but Buchanans could only get me matching Excels in WM4 and WM6; or Suns in WM4.5 and WM6. Don't understand why they can't get/make a WM5. I may decide to go WM3/19 front and WM4/18 rear like the 550, but wanted to go with a 110/130 18" combo on this bike. I will be pulling the fork tubes and the hubs this weekend. The tubes look pristine. New fork springs and Gold Valves going in. I think I will stay with the polished alum look for the fork legs, rims and hubs. Undecided on a front fender or bare with a Tarozzi - I have a spare one anyway. Going with a single instrument gauge - will be a surprise.

Blackfin5 · « **Reply #13 on:** January 31, 2014, 12:52:58 PM »

There has been some progress. The teardown of this phase is complete. As you know, the most fun is putting it all back together. I've been busy ordering parts, such as Sun rims, seat base, bearings, bushings, shocks, bars, lights, etc etc. I am finding 750 parts much easier to source than 550 parts.

The hubs, swingarm and steering head are getting new bearings and bushings. The grease in the steering head and swingarm has turned into a play-dough type muck. For new grease, I have been using Lucas Red & Tacky #2 and a EP Sta-Lube which has a 60 Timken rating (supposedly).

Luckily, the tapered bearings for the head arrived and today, I will be tapping in the races. I need to wait for the triple trees and stem to come back from PC.

Most of the frame's rust spots have been spot sanded and painted with the engine in place. Here, the tank was placed back on the frame while the fitment issues with the seat base are worked out.

The old bushings have been knocked out of the swingarm. It's been cleaned, sanded and given 3 coats of paint, with new bronze "self-lubricating" bushings and a yankee style zerk fitting. Jazz is a bit grogy from the paint fumes (kidding).

Like Tweakin, the seat base is from Airtech for a long-frame 750F. Although the product was nicely finished, I find it a bit too flimsy. I think if painted as is, I may end up with gel coat and/or stress cracks. Also, the separate rear tail light panel did not quite fit cleanly into the underside of the seat hump and the seat itself is too wide for the rear of the frame. I narrowed the seat a bit and reinforced the underside with 8oz carbon fiber. This was done earlier today. Once it sets up, I'll epoxy down a skin of bi-axial glass to the entire underside of the seat. Once this is finished, the tank, seat and new side covers are going to Manny, my painter. No fender - only a fork brace. The tank and body parts should come back from paint about the same time that my hubs and Sun rims should arrive. Went with a 2.15 front and a 2.75 rear both 18". In the meantime, the various engine covers are off and in for polishing.

Cheers!

Blackfin5 · « **Reply #14 on:** February 01, 2014, 10:17:27 AM »

Seat base modification is finished. It fits very well and I am happy with how the seat mates to the frame its entire length and with its rigidity after reinforcing the underside with carbon fiber and glass. In the photo there is a slight "V" at the juncture of the tank bottom line and seat base, but when bolted down, there is a perfectly staight line along the bottom edge. I pre-drilled the rear plate of the seat for my new tail light/turn signal LED combo, but I think I will wait to show that until after installed on the painted seat. As soon as the new side covers arrive from Franken's store, it's off to the painter and the seat pad off for black leather.

Blackfin5 · « **Reply #15 on:** February 01, 2014, 03:42:25 PM »

Two steps forward; one step back. I got my swingarm collar stuck going into the swingarm bushing with only about 1-1/2" of the collar in. I purchased a couple sets of bronze bushings from Charlie's Place in L.A. - Kibblewhite oil impregnated ones. I have spent considerable time on the swingarm. The new bushings went in cleanly with not too much effort. Plan was to bolt the swingarm back onto the bike today. I greased up the collar. It started in a bit tight so I gave it a few taps with the mallet. My bad. I didn't test fit the collar with the new bronze bushings before pressing them into the swingarm. I thought the old collar may be the issue, tweaked perhaps, but I grabbed a few bronze bushing I got from other sources and they all slid easily over the other end of the stuck collar - except for the other set from Charlie's. I'm kicking myself for not taking a few seconds to test fit the bushings over the collar. I don't think this is a case of the bronze bushing distorting at the median side from being pressed in the swingarm.

I'm so frustrated I called it a day. Will most likely have to heat up the bushing to get the collar unstuck, ruining the new swingarm paint in the process and will have to cut and knock out the Kibblewhite bushings and start over. If I can get the collar out without damaging the bushing, I will see if I can find someone to ream the ID of the bushings. I can't belive how stuck it is with only a few whacks of the mallet. I wiped off all the grease and pulled as hard as I could - nada.

edit......

Heated up the inside of the swingarm tube with a torch and blasted the protuding collar with freon. It came free after a few taps with a rod and mallet from the other end. I grabbed by buddy's collar from his 550 and the same - too tight. I tried my collar in his swingarm with new bronze bushings and it fit perfecly - can rotate it with zero play laterally. He got his bushings off ebay. I'll try to find a shop to spec the outer ends of my collar and open up the bushings' IDs with a line reamer to fit the collar. My amatuer spec-ing of the bushing ID is 0.84. I have no idea what it should be according to Honda.

Blackfin5 · « **Reply #16 on:** February 08, 2014, 08:24:15 PM »

This is getting frustrating ---- as said, 1 foot forward, 2 back. Broke the clutch lifter plate. I'm not a rookie in doing this. Alternating 1 turn of each bolt until the plate is uniformly seated against posts. I used my finer calibrated Sears Craftsman inch-pounds click handle torque wrench set to 96 inch-pounds once the plate was seated. Most here say no more than 10 foot pounds (120 inch lbs). The first 3 clicked off the torque wrench just fine, then "crack" on the 4th - still alternating about 1/4 each bolt. (Yes- the splines of the pressure plate were meshed in with the splines of the hub). I was trying to see if the spring coils were fully compressed - close, but not all the way. I chalk it up to a crappy torque wrench. Craftsman aint what it used to be. Or maybe it's because I was using new EBC +15% clutch springs (which were about 5/32nds longer than the stock ones I removed.

These lifter plates are difficult to find. Any suggestions? (Just found a NOS lifter plate and new bearing. You don't want to know the price.)

Blackfin5 · « **Reply #17 on:** February 08, 2014, 09:00:39 PM »

Step forward and a little bit of brightness - I got turned on to a machine shop in my town which does contract work for a sport and race bike shop in San Diego. They don't take walk-ins but my client owns the bike shop and he's going to ask the machine shop to line ream the bronze bushings. They will spec the outer ends of the collar (the end which actually which rides in the bushing) and ream the bushings to +1/1000 tolerance for a perfect grease cushion ride.

The step back (of course), the replacement US zerk fitting on the swingarm is slightly larger than the OEM (even though both are 6mm threads) and interferes with the back of the lower case with the swingarm installed. Geez.

Blackfin5 · « **Reply #18 on:** February 09, 2014, 05:54:05 PM »

Some progess today. Tank and tail faired and primed and going into paint in the morning. Welded in a small strap behind front of seat base for a little more security for bolting it down. Tail section has cut-outs for tail lights. Should have pics from painter by the weekend. Waiting for the Sun rims to be laced up and trued.

Blackfin5 · « **Reply #19 on:** February 11, 2014, 06:14:41 PM »

Some polished covers.

CB750R · « **Reply #20 on:** February 12, 2014, 03:57:48 PM »

I've broken two of the clutch plates myself. I had heavy duty clutch springs but went back to my old original ones as I found the after market ones longer as well. I've never found much info maybe the drag racers or road racers have a solution because as you I was very careful after having broken one, and then broke the second with trying to install the aftermarket springs.

tweakin · « **Reply #21 on:** February 12, 2014, 05:37:25 PM »

Nice. Looks like you are making progress. Keep it up.

Blackfin5 · « **Reply #22 on:** February 14, 2014, 08:16:45 PM »

Thanks, Tweakin. Spent some time this afternoon with a buddy working in the shop. 81 degrees here! This is his 550. Installed new tapered steering head bearings and his swingarm after pressing in bronze bushings. He powder coated his lower fork cases and going with a black clubman bar and rear sets. RaceTech fork springs. Everythng on the front end is only lossely fitted. He had his D.I.D. rims and hubs also powder coated black. They are being laced up with Buchanan SS spokes and chrome nipples at our "vintage MC shop" in S.D..

I'm not sure what make shocks he purchased, but he likes them which is what matters. China I'm thinking.

Blackfin5 · « **Reply #23 on:** February 14, 2014, 08:34:06 PM »

Today's progress on the Blaster: New billet upper triple tree (50mm offset) installed after installing new tapered steering head bearings. Even though I used a lower seal on my buddy's bike, I forgot to use a lower seal on mine. I realized my mistake after the first tap on the lower bearing on the frozen stem. An mere instant later I could not get it off. It seated with 1 light PVC tap. Oh well. Luckily I retained the stock lower seal which I stretched into the slot between the spacer and lower bearing. Seemed to work out fine. After tightening the bearing cover/cap over the upper bearing, to get the correct firmness, the stem rose too high above the upper triple. So unlike the 3 other sets of tapered bearings I've recently installed, I actually used the upper seal. Without the upper seal, I would have needed a thicker washer under the stem nut. Everything now lines up on the fork tubes in the exact same place as before.

Pic of tubes installed in new upper triple tree (powder coated upper and lower). New stem cap nut. I'm using clip ons. Don't have the ears for the headlight yet.

New polished aluminum sprocket arrived. Going with a 17/48 combo with a 530 D.I.D. x-ring 102 link gold chain.

Last for tonight, the NOS lifter plate and bearing arrived. Ouch! I'm not going to use the +15% clutch springs - not unless I have slipage issues, which I doubt. I will save them for Phase 2 which the HP gets boosted. The OEM springs spec out. I don't want to risk breaking another plate.

martin99 · « **Reply #24 on:** February 15, 2014, 06:16:45 AM »

You might want to do your mate a favour and refer him to the countless threads on here about those rear shocks. Not unknown for the lugs to break in use - don't bear thinking about $:-\$

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Author Topic: Blackfin CB750 F1 BLASTER (Read 28030 times)