Racing a Breva 750 in South Africa

[dbeerd]

I would like to field a Breva 750 in the South African “Battle of the twins” racing series. South Africans are snobs when it comes to Guzzi. My main reason for campaigning with the Breva is to score a few points in the season and show the other brands that Guzzi is still alive and kicking. The bike is stock standard. Now I need your help. How do I make it competitive? Please just remember that 1 euro = 10 Rand. That’s correct, whatever you buy will cost me 10 times more and then shipping and local tax laws still apply. Can anyone help with advice? :idea:

 

[GTM®]

OK, so what's your budget? Outside of tires, first you need to start with suspension work, then I recommend exhaust and fueling revisions (via Power Commander), and of course our sump spacer. If you want more power, you can check the main page HERE under Performance for small block modification. Other questions?

 

[dbeerd]

Hi, Thanks for the comments. The budget is whatever I can hide away from the wife. In respect of suspension setup what do you recommend as the Breva does not have adjustable front shocks. Should I change oil viscosity and amounts? I have a set of Minstral pipes on the bike currently, will this suffice with the standard headers, or should I make up a set of thicker header pipes? What about the exhaust balancer – connection pipe under the bike? Should this be removed? What piggyback EFI system do you recommend, model etc. I have access to milling facilities and a lathe – Thanks for the help - dion

 

[dbeerd]

come on chaps, help out here

 

[guzzigray]

OK. I'll bite.

Put the best tires on that you can afford and go thrash the crap out of it. And make it as crash proof as possible.

 

[dbeerd]

Thanks Bud

 

[Holt]

I've been on a raceway with my Breva.
Don't expect to be in front on the rakes, you'll take'em in the corners. :lol:

It's no phantom on the track, but you'll have fun anyway. Yes, better shocks and front end springs are good, dont race on Metzelers, Pirellis are better, and you may do this and you may do that but you won't gain many hp's but probably some more noise. Sound, as they call it.
Best thing to do is probably to loose weight, and that goes for the both of you.

 

[GTM®]

The budget is whatever I can hide away from the wife. In respect of suspension setup what do you recommend as the Breva does not have adjustable front shocks. Should I change oil viscosity and amounts? I have a set of Minstral pipes on the bike currently, will this suffice with the standard headers, or should I make up a set of thicker header pipes? What about the exhaust balancer – connection pipe under the bike? Should this be removed? What piggyback EFI system do you recommend, model etc. I have access to milling facilities and a lathe.

Dion, sorry for the timely reply... busy weekend/week so far. Done right, I'd recommend a set of ->HP fork springs & YSS PD Valves<-click and click->YSS shocks<-. The stock headers are just fine but you'll certainly want to replace the balancer/connector pipe, as it's basically a pre-muffler. I would modify the airbox by removing the lid or drilling as many large holes in it as possible, and you'll need a Power Commander to make it fuel properly... as well as a GuzziTech sump spacer to allow for more oil. This is essentially all I did to my first racing bike aside from tires... then as guzzigray says, make it crash-worthy and go ride, ride, ride. I'd be happy to help get you any of the pieces noted above.

 

[sign216]

Todd, I would like to learn a little more about the intake.

1. I thought air boxes were carefully tuned for resonance to maximize performance. Are the 750 airboxes not tuned, or just not tuned for the high rpm part of the power band that racers use?

2. I am a low rpm rider, who is after more torque. Will opening up the airbox hurt the low end torque, just like bigger valves would?

3. How about high flow air filters (like K&N brand). Are they a good option for a racer, or myself?

Joe

 

[GuzziMoto]

come on chaps, help out here

Take your front forks to a suspension guy to have them properly sprung and the dampening matched to the new springs. Very few racers use progressive springs, and that is for a reason. Look for someone who can set you up with a set of straight rate springs that are the right rate for you application. Who can do this in SA I don't know, but I am sure there is at least a few people who can. Try Ohlins people if you can't find someone. If you can only find progressive springs then fine, but keep in mind that preload affects rate and while the rate will change through the stroke the dampening will not. I would modify a set of stock springs first.
Then get a set of shocks that are set up/built for your weight and needs (i.e. racing). Your biggest gains in lap speeds will come from the suspension being right.
A sump spacer is a very good idea for a bike that holds so little oil. It won't make you go faster but it may keep you from blowing up the motor.
Todd's buddy Ed Milich knows way more about hot rodding the little Guzzi, but general hot rodding tips would be things like raise the compression (the stock motor is usually even lower then the low rating the factory says it has), improve the flow in and out of the motor (free flowing mufflers, better collector/cross-over, free flowing filter or none at all, and removing any intake snorkel or restriction of air into the airbox), and lightening up any spinning parts like the fly wheel as well as balancing/polishing the crank.
I would definitely work on the suspension first as this is where the biggest gains will come from. The motor work gets much more expensive for a given amount of speed. Removing every bit of weight you can is also a good idea.

 

[GTM®]

Todd, I would like to learn a little more about the intake.
1. I thought air boxes were carefully tuned for resonance to maximize performance. Are the 750 airboxes not tuned, or just not tuned for the high rpm part of the power band that racers use?

Joe, air boxes are developed for volume required to meet power requirements and sound restrictions...

2. I am a low rpm rider, who is after more torque. Will opening up the airbox hurt the low end torque, just like bigger valves would?
3. How about high flow air filters (like K&N brand). Are they a good option for a racer, or myself?

Opening the air-box lid provides more air-flow throughout the rev range, as shown in the bigger 1100 motor graph below. I recommend lid removal or modification to everyone, and yes, a high-flow elements such as K&N (or equiv.) is decent, though OEM paper filter elements are good when new. K&N has flow data comparisons on their website.

Power increase shown at wide open throttle with lid removed (blue trace) vs. stock (red trace):

 

[GTM®]

Take your front forks to a suspension guy to have them properly sprung and the dampening matched to the new springs. Very few racers use progressive springs, and that is for a reason. Look for someone who can set you up with a set of straight rate springs that are the right rate for you application.

Good advice, however I won three regional championships in the early 90's on a fairly stock Honda Hawk GT with Progressive Suspension springs and heavier oil (only) & a stock rear (horrific) shock. If he's looking to ease into it for fun, the above outline is the most cost effective way to do so. I can probably source a straight rate spring if it's critical, and the emulators are a decent bang for the $.

 

[GuzziMoto]

There is usually not a difference in price between straight rate springs and progressive springs. So it is not a money issue. It is just an issue of do you want a one size fits all spring that will likely be an improvement over stock or do you want a spring that is right for your application and will out perform the progressive spring.
Yes, you can go pretty quick even with progressive springs, I have used them as well. But progressive springs don't work as well as a proper set of straight rate springs matched to your application. It is just like tires, I have gone pretty quick on the stock OEM tires that came with the bike but I have always been able to go faster when using tires that are matched to my needs and riding style.
But as I said, if you can only find progressive springs then fine, use them. But I would rather spend the small amount of time and/or money to get my suspension the best I can as that is where the biggest improvement in lap times will come from as far as modifications to the bike.
But that is all just my opinion. You don't have to agree with me.

 

[Holt]

Guess you'd have to buy new forks if you want to make a real improvement on your Breva front end; the OEMs are not top-end forks, but prolly standard Marchozzis, and not adjustable in any means which is why springs are the the issue here, unless you've got a real thick wallet. - In which case you probably wouldn't race a Breva.
Using straight rate springs of course is better if you have a choice of sets made for different circuits and adjustable forks.
The OEM Breva springs are too soft for all kind of driving, so a swap to any standard available progressives will be an improvement in any case. Even more important are better shocks.

 

[GuzziMoto]

In the scheme of things, having a suspension guy set your forks up is not that expensive. It will likely cost you less then a quality set of shocks. Both of which are a very good idea if you want to race. Once you have the springs and dampening right it is much easier to go fast. And I never had to change springs for different tracks. Yeah, the top guys sometimes do that but they are on a different level and money is no object. Most club racers I know run the same straight rate springs the whole season. Almost nobody I know races with progressive springs. They are too much of a compromise. I am sure you can do it but the disadvantages out weight the advantages. An improvement over stock to be sure, but even modified stock springs can work better.
Yes you could buy a better set of forks, but you will still have to pay the suspension guy to set them up for your bike if you want to take advantage of the money spent on the forks. I would start with what you have and spend the lesser amount of money to make them work as well as they can before you go buying new forks.
In the long run having your forks and shocks optimized for your application is the least amount of money for the most amount of gain.

 

[guzzigray]

http://maxton.netspinners.co.uk/

These guys are the best. They take stock forks, gut them and install CBR600 cartridges. Cost is around 380 UK. They did the work on my Tonti racer and they are great. They make twin shocks too which are light weight replicas o Koni Dial A Rides.

 

[sign216]

Re: Air Box Modification

Todd, I would like to learn a little more about the intake.
1. I thought air boxes were carefully tuned for resonance to maximize performance. Are the 750 airboxes not tuned, or just not tuned for the high rpm part of the power band that racers use?

Joe, air boxes are developed for volume required to meet power requirements and sound restrictions...

2. I am a low rpm rider, who is after more torque. Will opening up the airbox hurt the low end torque, just like bigger valves would?
3. How about high flow air filters (like K&N brand). Are they a good option for a racer, or myself?

Opening the air-box lid provides more air-flow throughout the rev range, as shown in the bigger 1100 motor graph below. I recommend lid removal or modification to everyone, and yes, a high-flow elements such as K&N (or equiv.) is decent, though OEM paper filter elements are good when new. K&N has flow data comparisons on their website.

Power increase shown at wide open throttle with lid removed (blue trace) vs. stock (red trace):

I am disappointed that removing the air box lid improves performance. This means that Guzzi has not tuned the box for resonance to improve breathing. Tuning for resonance is free horsepower, that uses the natural frequency of the air box to boost air flow beyond that of an open air filter. See this:

http://www.calsci.com/motorcycleinfo/Airboxes.html

I can understand Guzzi not spending research money on the low-tech 750 engine (my favorite), but the dyno graph was for a Breva 1100, a more sophisticated machine that should be tuned.

Joe

 

[GuzziMoto]

Yeah, it is disappointing, but there is always a compromise when designing an airbox between what you want and space available.

 

[Holt]

I think the key words are, as Todd said, sound restrictions. Also emissions may be a part of it. EU rules for both noise and emissions have been tightened considerably over the past decade.

 

[sign216]

A good news/bad news situation. Bad that the air box isn't tuned, but good that you can still improve over factory performance by opening up the box. According to the dyno the performance gains are good for such a simple modification.

In a related vein, I'm going to ask in the tech section about cold air intake and ram air intake and see what people have done.

Joe