Re: Bigsam302's 76 CB750F w/GSXR Forks: Project Helen – She Lives!!!

[redwillissuperman]

Re: Bigsam302's 76 CB750F w/GSXR Forks: Project Helen - Finally, progress!!!

Any particular reason you picked the Mikuni RS over the Keihin?

 

[Bigsam302]

Re: Bigsam302's 76 CB750F w/GSXR Forks: Project Helen - Finally, progress!!!

Any particular reason you picked the Mikuni RS over the Keihin?

I did a lot of research on the carburetors when I was trying to figure out which ones I was going to use. Originally I was going to go with the Keihin, but I came across a few people who have built bikes with similar specs as mine that couldn't get the CRs to tune right. They ended up going with the Mikunis instead. Mikunis also seem to operate a lot smoother at lower RPMs due to the accelerator pump. To me, they just have better features. When I was planning my build, I spoke with Ken about it and he told me that I would see better results with Mikuni. I also spoke with a few guys over on another forum and they highly recommended the Mikuni over the CRs.

 

[DohcBikes]

Re: Bigsam302's 76 CB750F w/GSXR Forks: Project Helen - Finally, progress!!!

$$$$

 

[irk miller]

Re: Bigsam302's 76 CB750F w/GSXR Forks: Project Helen - Finally, progress!!!

No holds barred. 8)

 

[1fasgsxr]

Re: Bigsam302's 76 CB750F w/GSXR Forks: Project Helen - Finally, progress!!!

I hope I can get my CR's tuned right...making me think I made the wrong choice...

 

[Bigsam302]

Re: Bigsam302's 76 CB750F w/GSXR Forks: Project Helen - Finally, progress!!!

I hope I can get my CR's tuned right...making me think I made the wrong choice...

You may be fine and they should work well on your 350. I'm just comparing what I've been told from people who have big bore kits on their 750 (i.e., 836cc & 915cc). I am curious to hear how they work out for you.

 

[XVRacer]

Re: Bigsam302's 76 CB750F w/GSXR Forks: Project Helen - Finally, progress!!!

Nice work man. I really like watching a quality build.

 

[Bigsam302]

Re: Bigsam302's 76 CB750F w/GSXR Forks: Project Helen - Finally, progress!!!

The setback that I faced with the cylinder head stud will hopefully come to an end soon. The stud that I ordered off of ebay turned out to be the wrong one/size. I was very close to ordering another cylinder head off of ebay just to get the studs, but luckily MRieck was able to help me out. He saved my butt and some more money that I didn’t want to spend. He sent me a few studs and I should have them in a couple of days. Then I can continue installing my camshaft and degree it.

Since I couldn’t work on my engine, I decided that it was time for me to go ahead and tackle my oil cooler. Most of it was already assembled and all I had to do was just fit the hoses and connect it. I have the Cycle X spin-on oil filter adapter. I ordered my lines from Jaggs Oil Coolers. The kit came with hoses and clamps. If you look at the picture below, in the center of my setup is an automatic by-pass valve (also by Jagg). I like the way it turned out. Part of me wished that I had gotten the manual valve only because once I go to fill my bike with oil, none of it is going to make it to the cooler until the engine temperature rises. On the other hand, I would only need the manual valve once.

Here it is installed. I also installed the exhaust temporally just to check the clearance and everything works great.

Here is my oil filter(s). The black filter is the one that came with Cycle X’s spin-on kit. I am going to use this one first until I do the first break-in oil change. Then I will switch to the aluminum oil filter. The aluminum oil filter is also from Jagg. It is their Hyperflow Lifetime Oil Filter, meaning that it is reusable. It’s a pretty good quality setup and I can’t wait to try it out.

Here is a picture of it installed (only a test fit).

More updates to follow!

 

[redwillissuperman]

Re: Bigsam302's 76 CB750F w/GSXR Forks: Project Helen - Finally, progress!!!

I would maybe rethink the Emgo oil filter and use the aluminum or a very high quality brand. Break-in releases the most particulate, as well as heavy greases from assembly lubes etc. since you are using it for a limited time, and at limited RPMs, you could go down to a 10 or 20 micron. I would also use one of those hoaky magnets on the side.

 

[Bigsam302]

Re: Bigsam302's 76 CB750F w/GSXR Forks: Project Helen - Finally, progress!!!

I would maybe rethink the Emgo oil filter and use the aluminum or a very high quality brand. Break-in releases the most particulate, as well as heavy greases from assembly lubes etc. since you are using it for a limited time, and at limited RPMs, you could go down to a 10 or 20 micron. I would also use one of those hoaky magnets on the side.

Red,

Thank you for the advice! I hadn't thought about that, but you make a good point and I'll probably just go with my high end reusable oil filter.

Sam

 

[DohcBikes]

Re: Bigsam302's 76 CB750F w/GSXR Forks: Project Helen - Finally, progress!!!

Do NOT limit rpm during break in.

If you are not familiar with the proper procedures for high performance engine break in, i suggest you do some research before your very expensive engine is eating oil and getting hot.

Excellent advice on the filter.

Magnetic drain plug.

 

[irk miller]

Re: Bigsam302's 76 CB750F w/GSXR Forks: Project Helen - Finally, progress!!!

If this filter system is the same dimensions as the Hagerman CBX that Randakk sells, he has a list of compatible filters:

http://randakks.com/pages/oil-filter-conversion-kit-filter-fitments

 

[redwillissuperman]

Re: Bigsam302's 76 CB750F w/GSXR Forks: Project Helen - Finally, progress!!!

Do NOT limit rpm during break in.

If you are not familiar with the proper procedures for high performance engine break in, i suggest you do some research before your very expensive engine is eating oil and getting hot.

Excellent advice on the filter.

Magnetic drain plug.

There are two methods to determine the break-in procedure for a new engine:
- the first is to use the torque peak and to ride from 50% to 80% of the torque peak. Not applicable unless you have a bunch of development engines to create a torque curve from.

- second method is to break the usable rev range (say 0 to 9000RPM) into three 0-3000, 3000-6000, 6000-9000. For the first 500miles ignore the top rev range. You also want to spend a limited amount of time in the lower rev range, but this doesn't mean you can't allow the engine to idle, need to constantly blip the throttle, or can't slow down. It means don't lug the engine around town at 1500rpms. You want to ride on a long sweeping tour with the engine between 3000 and 6000. Accelerate at about 7/10ths to 6000 and slow down against the engine braking. Never full throttle, and turn your accelerator pumps down so you don't get cylinder washing. Never "jack rabbit", accelerating hard on and off, even in the rev range. Even on a straight road, picture you are careening up the California coast on a ribbon of road, you accelerate, hold constant, engine brake, hold constant, accelerate, repeat....you want everything up to temperature and you want to never turn off the engine at peak temp. But it is also beneficial to have everything go through a complete heat cycle after the first ride. If you go out for a 20minute ride on your sweeping road, then come back home through light traffic (not bumper to bumper), and park the bike. Leave it to cool completely, dead cold. check your valve clearances, bolt tightness, oil level, etc.

FYI: modern car and motorcycle engines usually don't require this break-in procedure any longer. Why? Most modern engines are run on a cyclotron (motoring dyno under air pressure), that breaks in the piston rings to cylinder wall, valve train etc. they also measure friction, cylinder pressure, and leak down. But I do swap out the lightweight 0W20 weight oil for 10weight ASAP. The lightweight oil is used for cold start emissions and not there for performance.

 

[redwillissuperman]

Re: Bigsam302's 76 CB750F w/GSXR Forks: Project Helen - Finally, progress!!!

The fun part is using the excuse that you need to "break-in" your motor to get out of chores and work. I find Thursday morning to be a great time to head into the mountains. Just tell your boss that you'll be out until Noon.

 

[DohcBikes]

Re: Bigsam302's 76 CB750F w/GSXR Forks: Project Helen - Finally, progress!!!

There are two methods to determine the break-in procedure for a new engine:
- the first is to use the torque peak and to ride from 50% to 80% of the torque peak. Not applicable unless you have a bunch of development engines to create a torque curve from.

- second method is to break the usable rev range (say 0 to 9000RPM) into three 0-3000, 3000-6000, 6000-9000. For the first 500miles ignore the top rev range. You also want to spend a limited amount of time in the lower rev range, but this doesn't mean you can't allow the engine to idle, need to constantly blip the throttle, or can't slow down. It means don't lug the engine around town at 1500rpms. You want to ride on a long sweeping tour with the engine between 3000 and 6000. Accelerate at about 7/10ths to 6000 and slow down against the engine braking. Never full throttle, and turn your accelerator pumps down so you don't get cylinder washing. Never "jack rabbit", accelerating hard on and off, even in the rev range. Even on a straight road, picture you are careening up the California coast on a ribbon of road, you accelerate, hold constant, engine brake, hold constant, accelerate, repeat....you want everything up to temperature and you want to never turn off the engine at peak temp. But it is also beneficial to have everything go through a complete heat cycle after the first ride. If you go out for a 20minute ride on your sweeping road, then come back home through light traffic (not bumper to bumper), and park the bike. Leave it to cool completely, dead cold. check your valve clearances, bolt tightness, oil level, etc.

FYI: modern car and motorcycle engines usually don't require this break-in procedure any longer. Why? Most modern engines are run on a cyclotron (motoring dyno under air pressure), that breaks in the piston rings to cylinder wall, valve train etc. they also measure friction, cylinder pressure, and leak down. But I do swap out the lightweight 0W20 weight oil for 10weight ASAP. The lightweight oil is used for cold start emissions and not there for performance.

Ignore the top rev range for the first 500 miles? Wheredya get that novel from, a chrysler car manual?

That is hands down the worst break in advice you could give him!!

Your engine is broke in well before the 100 mile mark.

There are a helluva lot more ways of breaking in an engine than just 2.

There is actually some good advice on engine break in here on the site, in a sticky somewhere. I don't feel like arguing with someone stuck in the dark ages on break in theory so try to find it if you care.

Or take the advice above and have an oil burner.

 

[DohcBikes]

Re: Bigsam302's 76 CB750F w/GSXR Forks: Project Helen - Finally, progress!!!

Some break-in banter from a few that know what they are doing: PLEASE READ AND FOLLOW.

With a fresh rebuild, assuming already that everything is properly assembled, pre lubed, and has arrived at operating temperature while slightly above idle to build and maintain oil pressure:

-Never rev a new engine with no load on it.

- It is cylinder pressure that forces the rings into shape, and the piston travel that matches them to the bore. High RPM under load is the best way to achieve even cylinder pressure and high piston speed.

- after the engine is warm, you need to get to it. Be ready to ride, accidents can be more likely when focusing only on the task of seating the engine components at high rpm, road hazards still exist. Have a place to ride it like it needs to be ridden, a track if possible. Firing it up and whomping it up and down your block is dumb.

-Safely enter a rural highway or track. Briskly throttle and get out of first gear, take it to a grand under redline through second, third, and fourth gear. You dont want to be in the lower rpm when you get into the next gear up, get those shifts made quickly.

- At a grand under redline in fourth, let the throttle snap shut and roll down through the rpm until it gets to a safe rpm to downshift, repeat through third and into second. Using no clutch to downshift is recommended.

-After the initial runup, go WOT to redline through as many gears as you can without endangering yourself or others. Do not miss any shifts. Let the trottle snap shut, roll down through the gears safely to second, and repeat.

Your engine is ready. Go ride it however you want to now. Run it the way you want it to run.

And DO NOT lug the engine.

I warm up 'new' motor at 2,000 rpm to make sure the oil is being thrown everywhere it needs to go, minute or so at first start isn't so bad as there will be assembly lube on all moving parts
Too much idling is really bad though, usually causes problems with small end of connecting rod which tends to 'go dry' and scuff and/or have partial seizure (seen it many many times)
I also chamfer the bottom edge of piston thrust face to direct more oil inside piston (rather than have the factory square edge)
I think it also helps cool piston crown?
Not as good as real oil jets but better than nothing
I think it may have been mentioned previously, it isn't a good idea to slather oil all over piston, rings and bore as your much more likely to get glazing of rings and cylinder.
It will bed in eventually but can easily take 20~30,000 miles
I use only a tiny bit of oil on piston skirt thrust face and a smear on the front below rings

In the 70's Honda made a films of bikes straight ff the production line being run through the gears and taken to red line before being dismantled and shipped
The main reason for 'break in' period was/is to try and get new riders used to new bike and it's foibles rather than a chance of engine damage

Take note 'warm up above idle'___'warm up the new motor at about 2000 rpm'___ 'too much idling is really bad'.

If you dont ride it hard it wont make the power you want and it will start using oil early in the service life. Do not baby that engine.

 

[Bigsam302]

Re: Bigsam302's 76 CB750F w/GSXR Forks: Project Helen - Finally, progress!!!

Thanks guys for the advice. Breaking in an engine is super confusing. There are so many different topics and opinions about the proper way to do it. This is what I was planning (I actually got this from a few other members with the same specs on another forum):

- After assembly, start the engine and allow it to idle slightly above normal idle speed. Allow the engine to come operating temperature and then rev it to 3000, 6000, and 9000 twice. Stop the engine and allow the motor to completely cool. Drain the oil, change the filter, and adjust valves.

- Refill with new oil, start the bike and let it get to normal operating temperature. Take it out on the road and do roll-ons and engine braking in third and forth gear. Let the engine rev to 1000 RPM under the redline. Repeat this a few times. Next go out and ride your bike!

 

[redwillissuperman]

Re: Bigsam302's 76 CB750F w/GSXR Forks: Project Helen - Finally, progress!!!

You procedure looks sound, but I would replace "rev the engine" with "drive the bike", taking it to those RPMs. You need the applied road load to resist the movement of the engine and apply stress to the internal engine components. That is why some people will say to find a long, sloping hill.

I'm the OE Engineer for many of the modern motorcycle and automotive engines so my tastes are more conservative. We spend millions of dollars developing procedures to ensure longevity for both the engine and the emissions, as required by the law. The procedure I gave you was paraphrased from one I just wrote for a small displacement powersports engine. Due to the cylinder type, we are not pre-bedding in the engine, and so I felt the procedure was applicable to your engine rebuild.

I would still recommend you stay away from full throttle, especially carbureted. Cylinder wash down is a real possibility. 7/10th throttle should be plenty of load.

 

[redwillissuperman]

Re: Bigsam302's 76 CB750F w/GSXR Forks: Project Helen - Finally, progress!!!

Here is the handy pictogram from the Ducati air-cooled Monster:

 

[DohcBikes]

Re: Bigsam302's 76 CB750F w/GSXR Forks: Project Helen - Finally, progress!!!

Do not rev the engine with no load.

This is not an oem application.

New cars are consuming more and more oil these days. Just sayin'.

Washdown is a possibility. I agree. This part i consider debateable, so WOT could be replaced with 'heavy throttle' in my explanation if you are concerned, as redline pulls do not require WOT. The possibility of wash down at WOT is more of a concern if you are not staying up in the revs.