PC800

[spacetiger]

I am getting close to finishing up the NH; only the chin spoiler and the hard cases, so it is time to thinking and planning out the completion of the 1990 PC800.

 - The front fork components and the brakes from a CBR600F4 are done.  They only need to be put on the bike.  I will explore larger dics (316mm) if I can get the spacers.
 
 - I have to put the rear disc brake, swing arm, and swap out the right rear shock.

 - I didn't get the VT1100 engine to work out because the cross drive was too thick so I couldn't get the engine centered AND get the output shaft top align to the swing arm.  So I am still stuck with the 57 HP engine unless I can come up with another option... and think I found it an option to explore - the VF700C (V4) engine.  The dimensions look doable in the PC800 frame, so I bought an tattered engine with carbs for $125 and will do some exploratory work in the month of April to see if I can get the engine aligned in the spare PC800 frame.  If I can get this to work, I can move up to 81 HP with a tad more torque than the stock engine.  This should be a suitable (43%) upgrade + the engine will stick out a bit under the radiator.   

The VT1100 engine is out of the frame now....

[bajakirch]

First time I've seen a PC800 with all of its clothes off. It looks...unseemly.

Good luck on the swap. What's the reasoning? -- everything I've heard about the PC800 has been pretty complimentary.

[PFox]

57hp stock? Sounds highly understressed, 800cc and only 57hp?

Turbooooooooooooo

 

[talespin]

I never dreamed that a PC800 looked like that under all the plastic.

I know the PC800 is one of those love/hate bikes, and I'm on the 'love' side. It may not the greatest bike ever made, but for some reason, it calls to me. Probably because it's not like every other bike out there.

[Boise Jim]

Interesting how the '97/'98 models look like the NT700.  Too bad the NT isn't more around 900cc, or a six speed. That would make it more attractive.

[spacetiger]

The NT has good power (more than the PC800) and a solid chassis.  The PC800 chassis is an interesting (modern) steel design where it wraps around the engine and runs from the neck to the swing arm pivot.  With the cross braces, it could be a decent handler but has low HP.  The engine is tuned for a broad torque band for relaxed riding.  An odd combination.  With the suspension and brake changes, I only lack an engine with a little more power to make it truly a little brother to the ST1100.

Jerry

[JimLob65]

The V4 is a really nice engine, and would wake up this bike nicely.  My 97 Magna 750 has a nice broad powerband, is very smooth, and is pretty darn quick.  Keep in mind not all Honda V4's are the same.  The later Magnas have chain drive, and the cylinders are rotated towards the back of he bike in relation to the rear wheel.  The older Magna and Sabre engines are shafties, with the front cylinders pointed much more towards the front tire.  Those cylinders would have to fit between the front frame rails.  Great project!!  Good luck and keep us informed!!

[marriedman]

No way! A Spacetiger PC? Awesome!

I am also on the love it side pf the PC's

[marriedman]

Jeesh, that engine looks pretty rough. Does it even turn?

[bhendron]

 

[spacetiger]

Jeesh, that engine looks pretty rough. Does it even turn?

Lol

This engine is not the final engine, it is the R&D engine.  For these kinds of effort, I like to reduce uncertainty as much possible before commuting the bigger $'s.  

The big risks are will it fit and how to fab the motor mounts.  For this task the engine is very good.  I will strip the inside and use only the shell and all external interfaces.  It even has carbs.  A good buy at $125.  An engine case would cost $60-50 alone.

BTW, you do realize that isn't a stock naked PC??

Jerry

[spacetiger]

The V4 is a really nice engine, and would wake up this bike nicely.  My 97 Magna 750 has a nice broad powerband, is very smooth, and is pretty darn quick.  Keep in mind not all Honda V4's are the same.  The later Magnas have chain drive, and the cylinders are rotated towards the back of he bike in relation to the rear wheel.  The older Magna and Sabre engines are shafties, with the front cylinders pointed much more towards the front tire.  Those cylinders would have to fit between the front frame rails.  Great project!!  Good luck and keep us informed!!

Yes Jim there are differences.  I am looking for most HP with shaft drive and straight out exhaust system.  I think 1986 is my target year.  87/88 are shaft options, but they come with the 4 into 4 exhaust system that will not work on the PC.  I am guessing by my research, the mounting interfaces are the same throughout the MY range. 

I do hope the engine points out a bit in front; I'll make sure it is tastefully finished off and the valve cover is nice and shinny.  That way, PC riders will wonder what is going on when they see it... 

Jerry

[JimLob65]

The V4 is a really nice engine, and would wake up this bike nicely.  My 97 Magna 750 has a nice broad powerband, is very smooth, and is pretty darn quick.  Keep in mind not all Honda V4's are the same.  The later Magnas have chain drive, and the cylinders are rotated towards the back of he bike in relation to the rear wheel.  The older Magna and Sabre engines are shafties, with the front cylinders pointed much more towards the front tire.  Those cylinders would have to fit between the front frame rails.  Great project!!  Good luck and keep us informed!!

Yes Jim there are differences.  I am looking for most HP with shaft drive and straight out exhaust system.  I think 1986 is my target year.  87/88 are shaft options, but they come with the 4 into 4 exhaust system that will not work on the PC.  I am guessing by my research, the mounting interfaces are the same throughout the MY range. 

I do hope the engine points out a bit in front; I'll make sure it is tastefully finished off and the valve cover is nice and shinny.  That way, PC riders will wonder what is going on when they see it... 

Jerry

Was the V45 a 750 in 1986, or a 700?  I think it was a 700 due to the tarriff on Japanese bikes over 700cc's.  Not sure though.

[spacetiger]

I believe the switch to go back to 750 happened on the 88 MY. 

The HP for the 700cc bikes was 81 HP @ 10,000 RPM.  The 87 700 engine dropped to 79 HP @ 9,500 RPM.  About the same power, so no reason to go for a bigger engine... unless I could shoehorn a V65 engine!

Jerry

[JimLob65]

According to a site I just checked out the switch happened in 1984.  That is why the Nighthawk S is a 700, not a 750.

[spacetiger]

Jim,

The switch to go from 750 to 700 did happen in 84.

The switch to go back from 700 to 750 happened in 88.

So, the 84-86 & 87 models were 700 cc.  

You are also correct in noting the V45 = 750cc.  The 700cc bikes were "V42", but that is not what they are called or badged as.

I think making my PC a 700cc machine, same displacement as my NH help identify me as an older rider as I am partial to those year bikes.

Jerry

[JimLob65]

Oops, sorry.  I misread your post.  Sorry about that!  Good luck to you on your project.  Hope you find one that works for you.

[spacetiger]

First time I've seen a PC800 with all of its clothes off. It looks...unseemly.

Good luck on the swap. What's the reasoning? -- everything I've heard about the PC800 has been pretty complimentary.

bajakirch,

The swap is to stretch the dynamic riding envelope of the bike.  The stock bike does a very nice job as intended, kind of like the 4 cylinder Accord with a 5 speed transmission.  

I have upgraded the suspension, [wheels]/Tires and brakes front and back on my 90 PC.  It lacks more punch from the drive train.  I figured the additional RWHP (up to 28 depending on year used) + close ratio transmission will do nicely.

Pic 1 is a dyno curve for the PC800... ~46 RWHP @ about 6,600 RPM, really it peaks at ~ 5,700 RPM at 45 HP.  You are just making more noise going another 900 RPM to make 1 more HP.

Pic 2 is a run of a 82-85 VF750S engine stock and after a jet change.  

Pic 3 is a super imposed combination of the rejected VF750S curve (blue line) vs. the PC dyno curve; ~28 RWHP gain (61% improvement)!  In fact, I think the engine power will feel similar to the PC engine, perhaps 2-3 HP more from idle to 5,600 RPM... then the VF750S engine will keep going up to 9,000 RPM pumping out lots more power.  I should be able to leave a stock PC in the dust with this little motor.  

Pic 4, the engine is out of the truck and into the garage.  I will tear apart the engine to remove everything inside to make it lighter.  In stock form, the engine weighs 186 lbs (PC engine weighs 176 lbs).  I hope to be able to strip out ~100 lbs so the dummy engine only weighs ~85 lbs.  That is an easier weight for me to move about while I'm trying to sort out the engine mounts.  I go get the spare PC frame this coming weekend; I hope the engine fits...

Jerry

  

[bajakirch]

Wow, that'll be akin to a minivan with a fully blown big block hidden under the hood.

[jerjohn]

 

[spacetiger]

Long day at work, so little progress tonight.

The rusty bits on the left and right side come off the iron engine tonight; needed the air gun.  

Carbs to come off and will drain any engine oil left tomorrow.  If the carbs come off without too much trouble, I will take the head bolts off.

Friday night , I pull the heads for sure and split the case and pull the guts out.

Sat morning, I strip all the non essential fitment items and reassemble the iron engine.

Sunday:  Take the remaining NH-S spare parts (I am declaring the NH-S done until this winter... except for a few minor things here and there) and go get the PC frame.

Jerry

[hppants]

There's a guy on Advrider.com that rides a rat-bike PC800 cross country (we're talking 100,000 miles plus).  He's very entertaining to read.

Looking forward to seeing the progress of your idea.  Personally, I'd rather ride the bike than re-design it, but I get you philosophy even if I don't agree with it.  Who knows, maybe you'll find a new market niche.

Good luck.

[Option13]

Personally, I'd rather ride the bike than re-design it, but I get you philosophy even if I don't agree with it.

Some of us enjoy wrenching. That's why you get two bikes.

[NightHawked]

Some have limited free time and would rather spend it riding and not wrenching or no more than necessary.

[Option13]

Who would think different people have different lives and hobbies?