CBR400RR - Spring Service...

[Iccle]

Day 11
Took the bike for a little Dyno Run this morning... unfortunatly I don't have anything previously to go off, but I was a little disappointed :>



I'm not entirely sure what going on here... I'm now not sure whether my poor bike has been running restricted for the last 4 years or whether I have a bit of a problem. To be honest whilst I've had the Tank & Airbox off, I've never had the Carbs off, and from what I've read the restrictor washers are between the Carbs & the Engine... So I'm gonna be having a look at that at the first possible oppertunity.

Furthermore, my old man had this to say...

What exactly does this mean?

The power graph starts out as you would expect but at speed there is so much instrument/electronic noise present that all you can do is run an average line through it. (Smooth the graph). Anyway both runs look consistent – trouble is the power band should be measured at different RPM and MPH has little to do with it, gearing etc? I will try to find the website that explains why MPH is not the preferred method of testing output power.

When I [used to] check out the Aero Engines [in Rolls Royce] they are on a static/sea level test bed, nothing to do with how fast they are flying and our customers paying £XYZ a motor will only accept this method. I am of course referring to helicopter engines which run through a gearbox to the rotor head.

Also, there are no legends on that printout showing any scales regarding your Air/Fuel Mixture... so again, Whats does this all mean?

Meh... I guess I've still got a little work to be doing just yet!

Day 12
Nothing done on the bike today, but I did take my daughter to get registered up at Southmead Hospital.

Besides, my MoT expired at midnight... lets pray for tomorrrow!

[scratchin]

should look something like this, i'd say its defo got restrictors fitted

[lazcbr29]

i would definately say its restricted.
if its running around 30bhp and a 105mph top end.
i'm 17 and on restricted license and my nc29 is around 33bhp.
they easy to pull put, like you said they are between the engine and the carbs.
laz

[Iccle]

Day 13 - MoT DAY!

MoT Passed... woopie! Big thanks to;

No advisories, straight pass... all the hard work my old man has done has paid off.


Anyway, after that was all done & finished, it was off to the "Guru's Garage" aka, the Parents.

Tank off, Air Box off... Filter cleaned, lets see these cabrs then...


I'm no expert, but I'm sure if I push back the Slides back, open the Butterflys (via the throttle), and have a good look down the Carbs I should be able to see the Restrictor Washers, right? Well, All I can see is the valves... all 4 per cylinder... no washers seem to be present at all... bugger.

Although, I did notice the choke cable was stuck, with the choke 25% open also... the cable is fooked... replacement ordered.


For now, my choke is represented by this lovely bit of Green Garden Wire... Getto yeah?

[missinNZ]

looking at your pic, ive had restrictors and cant remember looking down thru but why not take carbs fully off to make sure it only takes 15-20 mins to take off and put back on and they are down a bit looking at your graph i think youll find they are there? no shame in that choke mines the same except off the right side and luckily was a yacht rigger and made a nice nitronic s/s one up.

[Iccle]

...no shame in that choke mines the same except off the right side...

That is the right hand side, as you sit on the bike!

[trickyd400]

Another point to check is that the petrol tank breather in the cap is clear. I had a problem on my dyno runs due to having an NC30 petrol cap (which is unvented), and that the fuel pump is running(filter not blocked), gravity will fill the carbs but won't supply petrol fast enough for full power!

[Iccle]

Another point to check is that the petrol tank breather in the cap is clear. I had a problem on my dyno runs due to having an NC30 petrol cap (which is unvented), and that the fuel pump is running (filter not blocked), gravity will fill the carbs but won't supply petrol fast enough for full power!

A wise idea... I have new Fuel Hoses on order, as well as a new Fuel Filter... but I hadn't thought of checking the breather.

[Iccle]

Right then, where to start?

I fixed the choke cable two days after the MoT, no pictures though, DavidSilverSpares managed to get it to me in under 72hours.

Moving on, Easter Saturday was P-Day... all went quite well considering.

Firstly off came the tank, then we checked the Fuel Lines and the Pump. The Pump seems to be working perfectly, so no need to repair or replace although we didn't do a Flow Check, but it's opperating as it should so no real need.

Then we looked at the Fuel Lines... Fecking Honda... they are all moulded rubber. No chance of sticking anything other than genuine Honda ones back on so the two internal one (Carbs<Pump & Pump<Filter) were cleaned and put back on, but the Filter & Filter<Tank Fuel Line were replaced.

The old filter was actually very clear and in good condition, once I cleaned it all up. Before the above photo it looked shocking.

All looks really nice on the bike...


Hose is Braided Stainless Steel (15.5m OD) over a 10mm ID Low Pressure High Grade Rubber, capped with Sytec Hose Finishers. The Filter is a FSE Pro Inline Filter all bought from Demon-Tweeks, but researched at Fuel Systems.

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Iccle's Tips... Cutting Stainless Steel Braided Hose (without the proper tools).
You'll need:
1x Length of Hose (Normally sold in 1meter lengths), 2x Cable Ties, 1x Hacksaw with a New and Sharp Blade, 1x Reel of Masking Tape, Paper style is fine.

Firstly, measure the length of hose required. Then apply a band of masking tape, the middle of the tape being over the "end" of the length you require, as tight as you can.
Pull the two cable ties around the hose, over the masking tape but either side of where you want to cut, again as tight as you possibly can.
Using the Hacksaw (and a vice if you have one), cut slowly but forcefully throught the hose, turning it as often as possible. It helps to have something you can slide into the hose to stop it from compressing (we used a very long drill bit).
Once you've cut through the hose, and seperated the two "ends" you can cut the cable tie off the end of the length your using, keeping the other end "safe" for the time being.
If you have access you can use some Self-Amalgamating-Tape to wrap the end, over the masking tape, to tidy it all up.
Job Done.
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Now for the fun part, it seems that every time the pump "pulses" air bubbles come from the Pump to the Filter, which now being clear is easy to see... I'm guessing I've either got an airlock which will eventually clear or I'm pulling air from the carbs back through the system. I'm thinking the if it's the latter, my carbs need a full refurb.

As a final FYI, I've checked the Carbs again for washers, drilled slides, slides that don't open the whole way up or anything else... Nothing.

Here you can see down the stacks, past the slide (being held open gently by a pencil!) through the open butterfly and deep below are the visable valves.