1976 T3 to Le Mans Replica mini build

[Northern Bill]

I never noticed those pinstripes on the side panels but I will probably put some on as I have some left from the tank.

I put the pinstriping on after the clearcoat but I am no expert on this matter.

[canuck750]

Well that's how Guzzi did it as well, the side panels are pin striped over the paint and I know that Mandelo didn't cover them with clear either!

[thomas]

No one else has commented on the carbs so I will: the PO did you a real favour by fitting round-slide carbs similar to what was fitted to a real LeMans. The 850 T, the T3, the SP1000, the G5 and the CX100 all came with square-slide carbs.

The carbs are there for all to see, but it's the heads that still hide a secret. Did the PO keep the heads from the T3 (which have small valves)? Or did he also fit heads from a real 850 LeMans, which has bigger valves (so called mid-size valves)?

If the PO kept the T3 heads he would have had to use a stud-conversion kit, as the T3 had 8mm screws to fix the manifolds to the heads, while the LeMans manifolds require three 6mm screws.
If you got the real bargain and the LeMans carbs as well as the LeMans heads then a conversion kit was not needed and 6mm screws will be in use.

regards
Thomas

[Northern Bill]

As I mentioned earlier I am not all that mechanical so I am pleased to hear that the carbs are the real deal but I am curious to know if the 36mm round slide carb is actually better than the stock square carb. And I am really curious about the heads because I have yet to check them to see if they have the chrome bores so if they had been changed that would be a second bonus.  The bikes history is a bit of a mystery to me because I bought it from a fellow north of me who kept it well and had a lot of transmission work done prior to my getting it. Before that it was on the west coast of Canada on Vancouver Island and before that it was in Germany.
 
 I was out for a ride this morning and I had a chance to get out on the highway for a few miles.  I was surprised at how easily it could cruise along at an indicated 90mph.  I am also still surprised at how heavy, for me, this bike is.

[Northern Bill]

If the PO kept the T3 heads he would have had to use a stud-conversion kit, as the T3 had 8mm screws to fix the manifolds to the heads, while the LeMans manifolds require three 6mm screws.
If you got the real bargain and the LeMans carbs as well as the LeMans heads then a conversion kit was not needed and 6mm screws will be in use.

I went out and had a look at the manifolds on my t3 and there are 3 socket head screws attaching the manifold to the head.  I also looked in the Haynes manual on page 86, diagram3.3, and it looks like they are also using a manifold mounted with 3 socket head screws to mount a square slide carb. Am I correct in assuming that the difference in the heads is the size of the socket head screws?

[canuck750]

Am I correct in assuming that the difference in the heads is the size of the socket head screws?

The intake passage diameter on the LeMans was increased to match the carburetor size, other wise fitting 36mm carbs to a stock T3 head will offer no real benefit, same for the exhaust, porting of the heads is required to allow for the breathing. The larger diameter intake port resulted in less metal for the manifold bolts, hence the smaller diameter (6mm) manifold bolts on a Le Mans.

These are the manifolds on my 77 Le Mans

[Northern Bill]

Thanks for the pictures and the clarification. So, if I remove one of the socket head screws and measure it I should be able to tell if the bike has the Le Mans head?

[canuck750]

Thanks for the pictures and the clarification. So, if I remove one of the socket head screws and measure it I should be able to tell if the bike has the Le Mans head?

Yep, 8mm socket head bolts on most all Guzzi's and 6mm on the Lemans.

[guzzista]

Sorry to be a fly in the ointment, but I have seen quite a few T's , T3's SP's , CX,G5's  over the years that had TimeSerts or helicoils, 6mm Allen bolts while sporting LM manifolds with small valve heads. The real test is  measuring the valve diameter. ( 41/36 small valve, 44/37 LM1,2 )

[Northern Bill]

I was wondering about that.  In any case I am not too worried. I was corresponding with a company in England who specializes in Replicas using SP donors.  They said the replicas were easier to live with with the milder motors.

[Northern Bill]

I have been riding the bike for a while now and I have a few things that are unresolved.

1. I have checked the carbs for air leaks, checked the cables and springs, checked the advance on the distributor and everything seems to be good yet the rpms continue to drop very slowly, especially in the higher gears at over 4000 rpm. All seems to be well on idle and in first and second. In third if I am going along at 4000 rpm the bike acts like it is on cruise control ifI ease off the throttle but if I  twist the throttle back quickly the rpms drop a little faster.  The two 36mm carbs appear to be almost new.

2. I have a spot of fresh oil collecting on the top of the crankcases between the barrels. I wonder if this oil is coming from a breather pipe.

3. When I look at the bike from the side the mistake I made on the gas tank paint makes the front of the bike look like it is sitting higher but I also wonder if the bike is sitting higher.  Do you think pulling the fork tubes up through the triple clamps a half inch might help?
 

[thomas]

Hi
To your point No 1: have you checked the condition of your throttle cables? Do your throttles snap shut if you open them and let go, with the engine off?
If they are sticky, are they routed correctly?

[perter]

Nice build!

As for the bike sitting too high: Its a matter of taste but have a look at the bottom rails. I would think it would look more "mean" if you lower the front enough to keep them horisontal. On the other hand, the front springs are typical quite soft so the bike may look low on load.

I have mouted 36mm PHF on my SP1000 too. I found them a bit difficult to deal in and had starving issues too. What I propose you to do the following in this order:

1: Check for clogged internal tank filters. Mine were covered with some red stuff (rust) from years lack of cleaning. I cleaned the tank and put new filters in. Symptoms were it ran fine with full gas tank but was starving when I get below half full.....

2: Check for correct float level. Should be 18mm measured like on Fig 13: https://www.dellorto.co.uk/wp-content/uploads/2015/07/floatlevel.pdf

3: Make sure you have the right needle valve. I went from 250 to 300 and it gave a better flow.

4: What jets are you running? I found it hard to find a recommended combo for a SP1000 but with mine (including Lafranconi Competitione and K&N filters) I use 70 Idle, 140 mains (should probably be 135), AR268 atomizers and K18 needle, second lowest clip position.

If you use standard Lemans Manifolds there may be a step from the end of the manifold to the heads, around 1,5mm I think as the heads are 34mm at the end. It may not be a big deal but could create some turbulence?. I use a special made manifold with conic internal shape to overcome this step, got them from hmb-guzzi.com. This is though more icing of the cake and should not create the issues you mention IMO

[Northern Bill]

After riding the Guzzi for a while I decided it just wasn't for me.  I think I have made the transition to light bikes only. With the Guzzi sold I now own 2 two fiftys and 2 five hundreds and the heaviest one is about 350 pounds. My newest bike, a 2010 Kawasaki Super Sherpa weighs in at 280 pounds wet. Despite losing a bit of money on the T3 project I enjoyed the build and really liked the look of the finished product. I would definitely do it over again but being honest with myself I just enjoy riding my smaller bikes more. Thanks again for giving me advice along the way.

Although I have sold the bike, the build is not over because the new owner is having the bike painted professionally and he is having the rear wheel respoked.  He is going to take the bike to the next level.  When I see it next I will be salivating all over it!