Hello - Might get out my old Turbo again - Problems

Well, it's probably been 15 years since I have ridden my old Seca Turbo. I am thinking I may try and dig it out of the cobwebs again.

Here's what I have:

1983 Seca Turbo
1983 Maxim 750 Engine (very easy swap)
Stock Seca Carbs
Everything Else is stock (from what I remember)

I have actually gone through probably 4 of these engines over the years when I was riding them. They all ended up with second gear failures and most were smoking by the time that happened.

Anyway, I had eventually moved on to bigger bikes and was riding my Vmax by then so I wasn't too concerned with the Turbo. I can tell you that with the 750 engine and the turbo that it would run right with the Vmax when it was on the boost.

The last year I rode that thing was really bugging me. If I rode it normally the bike would run and drive fine. If I got into the boost for more then a gear or two the bike would run great until i slowed down and then it would die. It would not start until I waited a couple of hours later. I never did get that part sorted out. Also, towards the end I think the bike quit accelerating on boost and would only acclerate normally. As soon as boost would build the bike would stop running - back off a bit and it would pick up. I figure that is probably the fuel pump not able to keep fuel pressure above boost pressure.

Anyway, I'll clean the carbs out real well and maybe even look into swapping the pump out. Anyone have any good suggestions for a pump that would work well. Needs to have around 18-20lbs of pressure capability to keep 3lbs or so over the max boost.

On a side note. I did get a seca 900 engine probably 8 years ago to put into this beast. I figured with that engine and 15lbs of boost I should make around 150rwhp! Should be fun indeed!

Sean Morley

 

good luck

i'd look at your turbo, perhaps it needs rebuilt?

the boost sensor hose might be cracked / broke, this would affect the fuel pressure and such.

the sparkplugs might be bad as well as the carbs.

for the fuel pump, i have an aftermarket one, i believe the PO went to an autoshop store and said "i need this".. but it looks like a basic fuel pump.

I wouldn't think anything electronic, as it'd be more 'all the time'... idk though i'm no expert.

 

Before you spend a lot of money, try a few simple things. Take the hose off of the inlet to your fuel pump. There is a small plastic conical filter inside that fills with crap. After 25-26 years it is probably full of fluff, like mine was. Second, pull off the pressure hose going to the fuel pressure regulator. Spray some silicone lube in there, and apply some pressure with a bicycle pump. The regulator may have taken a "set" if it hasn't been actuating a lot. This cleared up the bucking/popping/backfiring I was getting on my old Seca when it came on boost. There were flames coming out the pipe, which, while fun to watch, weren't really helping to produce a whole lot of power. Make sure your wastegate isn't stuck open either.

Some turbo owners have commented that the seal on the gas cap deteriorates to the point where it will not allow the gas cap to vent properly, allowing a vacuum to build in the tank, preventing proper fuel flow, which could explain your bike dying after riding, and recuperating after a rest. Try taking your cap off if it does this and listen for an inrush of air into the tank.

 

I'll definitely look it all over when I get it pulled from the corner of the shop. If I have time I will try to get it at least back together like it is for our big dyno shootout in late June. I have 4 Vmax engines to build by then so not a lot of spare time.

Sean

 

Well, got it dug out on the lift. We got the carbs off last night and wow they are a mess! Not planning on doing much to the engine as of yet but wondered from everyone what might be a good preventative to do or check before we fire this sucker back up.

We are going to drain the fluids and change the plugs of course.

I need to find the thread with who sells the carb parts too and get them on their way.

Sean

 

chacal is our parts guy

 

We are taking the carbs apart now and man they are nasty! I am going to try just plain water in the ultrasonic tank this time around to see what it can do. If I don't like it I'll do it in the pro chemical solution I have. Maybe I'll get some pics up soon.

Sean

 

Got my new parts from Chacal (thanks for the speedy service). Been working on other stuff on the chassis (as well as my normal Vmax work). Got the valve cover off and it's still nice and clean inside. Need 1 more shim to complete the valve adjustment. I just don't have many to pick from.

Got the oil drained but not refilled. Took off the master cylinder cover and found jello (at least that's what it looks like). Line actually has fluid so should only need to bleed it real well once we get the master cleaned.

I think the rest of the chassis is fine and even the tires don't look weathered. The bike has been kept inside all these years which has helped preserve it a bit.

I will eventually get some pics and post them up.

Sean

 

As another Sean and another turbo owner, Have fun with the turbo!!. I doubt I would do the swap from the 650 turbo engine to the seca 750 engine since the turbo engine is much stronger internally. Stronger bottom end at least. If you wanted to try to swap out the pistons and the head it would be doable, however I imagine you would have to use the stock turbo cams and the intake manifolds. The intake manifolds use an o-ring between the manifold and the head unlike the normally aspirated seca's which use just a gasket. Have fun with it and keep us posted, also check out Turbo message boards.

Sean

BTW did most of your teachers ask for Seen???? ROFLMAO!!

 

Seen - exactly!

I have installed 4 different 750 engines in this chassis over the years and it currently has a 750 Maxim engine in it. The transmission is the weak link on them and they have not given any other failures other then breaking driveshafts (probably broken a dozen of them).

All I had to do for the swap was drill and tap for the oil return and knock sensor (if I remember right). Then swap the oil pan and pump. Other then that I don't think I had to swap anything else. I know I didn't get any farther int the engine other then the pump.

Turbo seemed to take a bit longer to spool but when it came on it was intense! Would power wheelie through 3 gears. I can tell you that it was as fast as my Vmax was when it was on the boost.

I drag raced it many years ago with the stock engine and want to say it was running low 12's with traction issues.

Sean