Author Topic: 1977 cb750f2 (915cc) (Read 235867 times)

FunJimmy · « **Reply #700 on:** February 18, 2012, 12:28:15 pm »

Aw Man! Don't tell me you changed your identity and moved before we had a chance to ride the Cascade Loop. Chicken.

tweakin · « **Reply #701 on:** February 19, 2012, 05:53:11 am »

No chance I am missing that ride. Only thing I am afraid of is the amount of IPA's I will consume in your presence...

Quote from: FunJimmy on February 18, 2012, 12:28:15 pm

Aw Man! Don't tell me you changed your identity and moved before we had a chance to ride the Cascade Loop. Chicken.

tweakin · « **Reply #702 on:** March 05, 2012, 06:35:05 pm »

Minor set back with the bike but all is great know. The 915 was running excellent with the exception of needed to be tuned but I was not getting 4th or 5th gear.

I must have done something wrong when I shift tumbler / forks back together. The good news I feel like there is nothing I can't do on these bikes now.

Yanked the engine.

Split the cases and fixed the shifting.

Got everything buttoned back up with out a hitch and it shifts better than any cb I have ever been on, something to be said about taking my time.

I also was able to get close to what I thing is optimal tuning of the RS34's by following Doctor D's guidance, thanks. 132.5 mains, 9DZH03 needles middle clip position, 120 pilots and air screw 1/2 turns out. Synched the carbs and it has more power, seat of the pants, than I could have ever imagined... Only a proper dyno tune will tell the entire story onc it is good and broken in.

On another note I picked up my next project, a 1978 cb750f from member Jaguar, Thanks!

The plan for this bike is to make a nice semi stock daily rider with all my take off bits from this build including the 836 engine and CR29's I have waiting.

liPPy · « **Reply #703 on:** March 05, 2012, 06:51:43 pm »

What was the shifting issue you had and how did you fix it?

New project looks interesting

tweakin · « **Reply #704 on:** March 05, 2012, 06:59:28 pm »

My shift drum installation was just a bit off causing the forks to bind. Pretty easy fix once the cases were split.

Quote from: liPPy on March 05, 2012, 06:51:43 pm

What was the shifting issue you had and how did you fix it?

New project looks interesting

MCRider · « **Reply #705 on:** March 05, 2012, 07:03:30 pm »

Quote from: tweakin on March 05, 2012, 06:59:28 pm

My shift drum installation was just a bit off causing the forks to bind. Pretty easy fix once the cases were split.
Quote from: liPPy on March 05, 2012, 06:51:43 pm
What was the shifting issue you had and how did you fix it?

New project looks interesting

Man That's just the kind of thing that worries me. I can't picture your problem. I have shifted mine thru all 5, but that's not conclusive until it's actually running. Or maybe mine will just puke oil out of every crevice, who knows?

Good work, anyway!

tweakin · « **Reply #706 on:** March 05, 2012, 07:33:36 pm »

You will be fine, mine shifted thru all gears but it was real rough in 4 and 5. The second time around it was like butter...

Quote from: MCRider on March 05, 2012, 07:03:30 pm

Quote from: tweakin on March 05, 2012, 06:59:28 pm
My shift drum installation was just a bit off causing the forks to bind. Pretty easy fix once the cases were split.
Quote from: liPPy on March 05, 2012, 06:51:43 pm
What was the shifting issue you had and how did you fix it?

New project looks interesting
Man That's just the kind of thing that worries me. I can't picture your problem. I have shifted mine thru all 5, but that's not conclusive until it's actually running. Or maybe mine will just puke oil out of every crevice, who knows?

Good work, anyway!

lucky · « **Reply #707 on:** March 05, 2012, 09:45:47 pm »

Quote from: MCRider on March 05, 2012, 07:03:30 pm

Quote from: tweakin on March 05, 2012, 06:59:28 pm
My shift drum installation was just a bit off causing the forks to bind. Pretty easy fix once the cases were split.
Quote from: liPPy on March 05, 2012, 06:51:43 pm
What was the shifting issue you had and how did you fix it?

New project looks interesting
Man That's just the kind of thing that worries me. I can't picture your problem. I have shifted mine thru all 5, but that's not conclusive until it's actually running. Or maybe mine will just puke oil out of every crevice, who knows?

Good work, anyway!

When the trans and shift drum is together, you can turn it by hand and tell if it will shift properly.
Matter of fact that is a must do.

Greggo · « **Reply #708 on:** March 05, 2012, 09:46:56 pm »

Nominated.

http://forums.sohc4.net/index.php?topic=103091.0

tweakin · « **Reply #709 on:** March 06, 2012, 04:44:05 am »

Quote from: lucky on March 05, 2012, 09:45:47 pm

When the trans and shift drum is together, you can turn it by hand and tell if it will shift properly.
Matter of fact that is a must do.

Doctor_D · « **Reply #710 on:** March 06, 2012, 06:46:28 am »

Quote from: tweakin on March 05, 2012, 06:35:05 pm

I also was able to get close to what I thing is optimal tuning of the RS34's by following Doctor D's guidance, thanks. 132.5 mains, 9DZH03 needles middle clip position, 120 pilots and air screw 1/2 turns out. Synched the carbs and it has more power, seat of the pants, than I could have ever imagined... Only a proper dyno tune will tell the entire story onc it is good and broken in.

Glad to hear that it feels stronger. Keep an eye on your accelerator pump plunger, they have a habit of not coming all the way back up.

cheapride · « **Reply #711 on:** March 06, 2012, 08:14:24 am »

See splitting the cases isn't that bad just a waist of the weekend. Did you have your neutral switch in when you first installed the shift drum and forks? Mine wasn't in until after and it made it a little more difficult. With your CR's do you use the factory carb boots or do they have new ones?

tweakin · « **Reply #712 on:** March 06, 2012, 08:26:07 am »

Splitting the cases is really easy, just a pain. Yes, I always have my neutral switch in when putting the drum and forks in. This time I follows Hondanlmans instructions and all went smooth.

The CRs use the stock boots, luckily mine were in good shape just needed to be softened up a bit with wintergreen.

Quote from: cheapride on March 06, 2012, 08:14:24 am

See splitting the cases isn't that bad just a waist of the weekend. Did you have your neutral switch in when you first installed the shift drum and forks? Mine wasn't in until after and it made it a little more difficult. With your CR's do you use the factory carb boots or do they have new ones?

MRieck · « **Reply #713 on:** March 06, 2012, 08:52:57 am »

Quote from: Doctor_D on March 06, 2012, 06:46:28 am

Quote from: tweakin on March 05, 2012, 06:35:05 pm
I also was able to get close to what I thing is optimal tuning of the RS34's by following Doctor D's guidance, thanks. 132.5 mains, 9DZH03 needles middle clip position, 120 pilots and air screw 1/2 turns out. Synched the carbs and it has more power, seat of the pants, than I could have ever imagined... Only a proper dyno tune will tell the entire story onc it is good and broken in.

Glad to hear that it feels stronger. Keep an eye on your accelerator pump plunger, they have a habit of not coming all the way back up.

I wonder if a stronger diaphragm spring would take care of that Dave? The rubber gaiter may have something to do with that too.

Doctor_D · « **Reply #714 on:** March 06, 2012, 04:26:50 pm »

Quote from: MRieck on March 06, 2012, 08:52:57 am

Quote from: Doctor_D on March 06, 2012, 06:46:28 am
Quote from: tweakin on March 05, 2012, 06:35:05 pm
I also was able to get close to what I thing is optimal tuning of the RS34's by following Doctor D's guidance, thanks. 132.5 mains, 9DZH03 needles middle clip position, 120 pilots and air screw 1/2 turns out. Synched the carbs and it has more power, seat of the pants, than I could have ever imagined... Only a proper dyno tune will tell the entire story onc it is good and broken in.

Glad to hear that it feels stronger. Keep an eye on your accelerator pump plunger, they have a habit of not coming all the way back up.
I wonder if a stronger diaphragm spring would take care of that Dave? The rubber gaiter may have something to do with that too.

The plunger actuator (on the throttle shaft) is also on a spring, so too strong a plunger spring may cause other problems. Maybe some silicone on the plunger shaft, where it passes through the gaiter will help. If that doesn't work, I'm going to try a slightly heavier spring.

cheapride · « **Reply #715 on:** March 07, 2012, 07:05:41 am »

Quote from: tweakin on March 06, 2012, 08:26:07 am

The CRs use the stock boots, luckily mine were in good shape just needed to be softened up a bit with wintergreen.

How long does the winter green or thor oil tire prep take before the boots are soft?

Lostboy Steve · « **Reply #716 on:** March 07, 2012, 07:12:16 am »

Hey man, whats the inside coated with? You should have someone laminate a picture of that engine split and hang it somewhere on the bike so people can see how beautiful it is inside once together. lol I'm not joking the inside looks nicer than most outsides do!

tweakin · « **Reply #717 on:** March 07, 2012, 08:34:43 am »

I used wintergreen and hot water on the stove and opted not to use xylene.

http://forums.sohc4.net/index.php?topic=62328.50

Quote from: cheapride on March 07, 2012, 07:05:41 am

It has been awhile so I can not remember how long I had them simmer in the mix. The above thread should be some help.
Quote from: tweakin on March 06, 2012, 08:26:07 am
The CRs use the stock boots, luckily mine were in good shape just needed to be softened up a bit with wintergreen.

How long does the winter green or thor oil tire prep take before the boots are soft?

tweakin · « **Reply #718 on:** March 07, 2012, 08:37:57 am »

Ha Ha, the coating is Glyptal, it is made for coating the inside of engine parts.

Quote from: twistedengineering on March 07, 2012, 07:12:16 am

Hey man, whats the inside coated with? You should have someone laminate a picture of that engine split and hang it somewhere on the bike so people can see how beautiful it is inside once together. lol I'm not joking the inside looks nicer than most outsides do!

tweakin · « **Reply #719 on:** March 07, 2012, 03:13:47 pm »

The sun was finally out today in the PNW so I took the day of and put some miles in on the new engine. I am still trying to figure out the correct angle to mount my GoPro to my helmet so this is an interesting view. Sorry if the video make some of you dizzy

. Bike is running great and now have all 5 gears, the initial part of the video is at 2X speed so my bike doesn't really idle at that speed... Looking forward to some open roads and the engine to be completely broken in so I feel comfortable at the higher rpm's, but you can get an idea.

1977 cb750f / 915

brandEn · « **Reply #720 on:** March 07, 2012, 04:06:09 pm »

phukin cool man. How do the clipon/rearsets feel?

tweakin · « **Reply #721 on:** March 07, 2012, 08:04:04 pm »

felt great B. I really like the new riding position.

Quote from: brandEn on March 07, 2012, 04:06:09 pm

phukin cool man. How do the clipon/rearsets feel?

immortal · « **Reply #722 on:** March 08, 2012, 09:29:24 am »

Awesome job tweakin!

Godffery · « **Reply #723 on:** March 08, 2012, 03:22:19 pm »

Absolutely outstanding work man...!

messeduptriple · « **Reply #724 on:** March 08, 2012, 03:49:39 pm »

Wow...I only wish I knew how to tear apart an engine and do a build like that. Great work and awesome bike!!!

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Author Topic: 1977 cb750f2 (915cc) (Read 235867 times)